THE  ROMANCE 

OF  MODERN 

ELECTRICITY 


CHARLES 
GIBSON 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


By  permission  oj 


Ciesserei  Bern,  Switzerland 


PASSENGER  HOIST  ON  THE  WETTERHORN 

One  car  is  ascending  while  the  other  is  descending.  The  cars  are  drawn  by  a  cable 
passing  through  the  upper  station,  which  is  seen  in  the  top  left-hand  corner  of  the 
photograph.  This  house  contains  an  electric  motor  which  drives  the  cable,  while  the 
electric  current  is  supplied  very  conveniently  from  a  lower  station.  A  photograph  of 
the  upper  station  is  shown  facing  page  20. 


THE  ROMANCE  OF 
MODERN  ELECTRICITY 

DESCRIBING    IN    NON-TECHNICAL 

LANGUAGE  WHAT  IS   KNOWN  ABOUT 

ELECTRICITY   AND    MANY    OF    ITS 

INTERESTING  APPLICATIONS 


BY 


CHARLES   R.  GIBSON,  F.R.S.E, 

AUTHOR  OF  "ELECTRICITY  OF  TO-DAY" 

"THE  ROMANCE  OF  MODERN  PHOTOGRAPHY" 

"SCIENTIFIC  IDEAS  OF  TO-DAY,"  ETC. 


NEW  &  REVISED  EDITION 


WITH  THIRTY-FOUR  ILLUSTRATIONS 
S*  THIRTEEN  DIAGRAMS 


PHILADELPHIA 
J.    B.    LIPPINCOTT    COMPANY 

LONDON:    SEELEY  &  CO.    LIMITED 
1910 


PREFACE 

TO  THE  REVISED   EDITION 

THE  first  edition  of  this  work  was  published  towards 
the  end  of  1905,  and  while  repeated  editions  have 
been  called  for,  these  have  been  merely  reprints. 
But  things  move  quickly  in  the  electrical  world,  and  since 
the  first  edition  was  published  much  has  happened  in 
several  departments.  Wireless  telegraphy  has  made  great 
strides,  and  wireless  telephony  has  passed  from  the  ex- 
perimental stage  into  the  business  world.  A  good  deal  of 
new  matter  has  been  added  in  connection  with  these ;  an 
entirely  new  chapter  having  been  added  on  wireless  tele- 
phony. Owing  to  very  interesting  advances  in  the  working 
of  telephone  exchanges,  the  greater  part  of  Chapter  XIV 
is  new.  Then  our  ideas  concerning  the  inner  nature  of 
electrical  phenomena  have  been  extended  very  considerably 
by  the  advent  of  the  electron  theory ;  a  good  deal  of  new 
matter  has  been  added  in  this  connection.  In  addition  to 
these  matters  the  whole  text  has  been  carefully  revised  so 
that  it  covers  any  new  ground. 

The  author  is  indebted  again  to  Professor  Magnus 
Maclean,  MA.,  D.SC.,  F.R.S.E.,  for  very  kindly  reading  the 
proof-sheets.  Also  to  William  Allan,  A.M.I.E.E.  (Chief 
Electrician  to  the  National  Telephone  Company  in 
Glasgow)  for  reading  the  chapters  dealing  with  telephony. 
And  to  J.  Erskine-Murray,  D.SC.,  F.R.S.E.,  M.I.E.E.  (Consult- 
ing Wireless  Telegraphist)  for  reading  those  chapters 
relating  to  communication  through  space. 

5 

227547 


PREFACE 

TO   THE   FIRST   EDITION 

THE  younger  members   of  the  present  generation 
have  become  so  accustomed  to  the  practical  appli- 
cations of  electricity  that  it  is  very  difficult  for 
them  to  appreciate  the  marvellous  difference   that   the 
advent  of  electricity  has  made  in  everyday  life. 

If  the  present  conditions  of  life  had  been  correctly 
predicted  a  few  generations  ago,  the  prophet  would  have 
received  little  attention,  or  would  have  been  made  a 
laughing-stock.  It  certainly  would  have  seemed  quite 
incredible  that  people  would  some  day  be  able  to  send 
messages,  with  lightning  speed,  across  the  seas  to  the  very 
ends  of  the  earth,  and  learn  in  return  what  was  actually 
taking  place  there  at  the  very  moment,  instead  of 
waiting  many  weary  weeks  for  news  to  be  carried  by  road 
or  sea.  It  would  have  seemed  even  more  impossible  that 
people  would  ever  be  able  to  carry  on  actual  conversation 
with  friends  distant  many  hundreds  of  miles  from  them. 

While  the  simple  phenomena  of  the  lodestone  and  the 
rubbed  amber  were  known  to  the  people  of  many  centuries 
ago,  little  did  they  dream  then  that  these  feeble  pro- 
perties would  soon  be  increased  to  a  gigantic  power, 
which  would  propel  great  heavy  vehicles  across  the 
country,  each  carrying  many  hundreds  of  passengers.  No 
one  would  have  thought  that  electricity  would  serve  to 
light  up  the  darkness  of  great  cities. 

6 


PREFACE 

If  one  had  foretold  that  all  this  immense  power 
required  for  propulsion,  or  for  lighting,  would  be  trans- 
mitted along  a  solid  and  stationary  wire  stretched  between 
two  distant  places,  there  would  have  been  many  people 
willing  to  declare  that  such  a  thing  was  against  all  the 
laws  of  nature. 

It  is  very  doubtful  if  the  most  optimistic  philosopher 
of  a  century  ago  would  have  believed  that  this  so-called 
electricity  would  enable  the  physicians  of  the  future  not 
only  to  see  and  photograph  each  bone  and  joint  in  the 
living  skeletons  of  their  patients,  but  also  to  see  and 
watch  the  movements  of  the  heart  and  other  organs  of 
the  human  body. 

The  present  generation,  having  grown  up  amidst  all 
these  and  other  wonders,  has  almost  ceased  to  marvel  at 
them.  If  the  ordinary  man  of  business  stops  to  think  of 
them,  how  often  does  he  pass  them  over  as  things  not 
easily  understood,  and  rest  content  to  take  things  as  he 
finds  them  without  questioning  the  why  and  wherefore. 
However  difficult  it  may  be  to  discover  what  electricity 
really  is,  there  is  no  reason  why  both  young  and  old 
should  not  understand  how  it  is  harnessed  and  made  to 
do  useful  work. 

The  hurly-burly  of  present-day  life  is  so  great  that  few 
have  the  time,  or  the  inclination,  to  study  the  subject  in 
scientific  text-books,  but  the  author  hopes  to  show  in  the 
present  volume  that  some  clear  understanding  of  the  sub' 
ject  may  be  obtained  in  a  simple  and  pleasant  manner. 


AUTHOR'S  NOTE 

THE  author  is  indebted  to  Professor  Magnus  Maclean, 
M.A.,  D.SC.,  F.R.S.E.  (Professor  of  Electrical  Engineering 
in  the  Glasgow  and  West  of  Scotland  Technical  College), 
for  very  kindly  reading  the  proofs,  and  to  Dr.  Lee  de 
Forest  and  the  National  Electrical  Signalling  Co.,  U.S.A., 
for  particulars  regarding  their  respective  systems  of  wire- 
less telegraphy. 

In  connection  with  the  illustrations  the  author  is  in- 
debted to  the  following  firms,  journals,  and  individuals; 
Siemens  and  Halse,  Siemens  Schuckert  Werke,  Berlin ; 
Wilhelm  Fiille,  Barmen;  The  Automatic  Electric  Co., 
Chicago ;  The  Scientific  American,  New  York ;  The 
National  Electric  Signalling  Co.,  U.S.A.;  The  Electrical 
Co.,  Ltd.;  The  Electrical  Magazine;  Merry  weather  and 
Sons,  Ltd.;  The  India  Rubber  and  Telegraph  Works  Co., 
Ltd.,  London ;  The  National  Telephone  Co.,  Ltd. ;  The 
Glasgow  Corporation  Telephone  Department ;  Mavor  and 
Coulson,  Ltd. ;  Giesserei  Bern,  Switzerland ;  Richard 
Kerr,  F.G.S.,  F.R.A.S.  ;  John  M.  B.  Taylor ;  John  White- 
side  ;  Alex,  McGrouther ;  and  Mr.  Stacey,  Dunmow. 


CONTENTS 

CHAPTER  I 

PAGE 
THE   PART   PLAYED   BY    ELECTRICITY          .  .  .          .         15 

CHAPTER  II 

HOW  WE  CAME  TO   KNOW  ABOUT  ELECTRICITY      .  .          .        2O 

CHAPTER  III 
How  BATTERIES  WERE  INVENTED          .  .  ,       .      26 

CHAPTER  IV 
WHAT  is  MAGNETISM?  .  •  ...      38 

CHAPTER  V 
How  MAGNETISM  is  RELATED  TO  ELECTRICITY   .  47 

CHAPTER  VI 

HOW   WE  CAME  TO   HAVE  THE  TELEGRAPH  ,  .          .        52 

CHAPTER  VII 

HOW  WE   NOW  SEND   TELEGRAMS  •  .  62 

CHAPTER  VIII 
TELEGRAPHING  ACROSS  THE  SEA  •  •  .      74 

CHAPTER  IX 

SOME  EARLY  ATTEMPTS   AT  TELEGRAPHY  ,  87 

CHAPTER  X 

TELEGRAPHING  THROUGH  SPACE  «  .          ,       »     94 

9 


CONTENTS 

CHAPTER  XI 

FAGS 

ELECTRICITY  IN  NATURE  .  .  .          .       «    106 

CHAPTER  XII 
INTERESTING  APPLICATIONS  OF  ELECTRICITY        .          .       .    115 

CHAPTER  XIII 
FURTHER  APPLICATIONS  OF  ELECTRICITY  ,  .    127 

CHAPTER  XIV 
ELECTRICITY  AND  SPEECH         .  .  •  •       .    139 

CHAPTER  XV 

WIRELESS  TELEPHONY  .  .  ...     162 

CHAPTER  XVI 
INDUCTION  COILS  EXPLAINED    .  •  ,  «    167 

CHAPTER  XVIJ 

LIGHT  THAT  DOES  NOT  AFFECT  THE  EYE  .  .    174 

CHAPTER  XVIII 
How  ELECTRICITY  PRODUCES  LIGHT      .  •  •       •    182 

CHAPTER  XIX 
ELECTRICITY  FROM  MECHANICAL  MOTION  .  .    193 

CHAPTER  XX 
MECHANICAL  MOTION  FROM  ELECTRICITY  ,  .    203 

CHAPTER  XXI 
ELECTRIC  RAILWAYS,  NIAGARA,  ETC.      .  ,  .    212 

CHAPTER  XXII 
ELECTRICITY  IN  THE  OBSERVATORY        .  »  ,        .    224 

CHAPTER  XXIII 
ELECTRICITY  AND  THE  PHYSICIAN  .  ,          ^     .    236 

CHAPTER  XXIV 

ELECTRICITY  AND  RADIUM        .  •  .    243 

10 


CONTENTS 

CHAPTER  XXV 

PACK 

ELECTRICITY  AND  CHEMISTRY  .  .  »          •  254 

CHAPTER  XXVI 
ELECTRICITY  IN  THE  COAL-MINE  .  •  •       .    263 

CHAPTER  XXVII 
ELECTRICITY  AS  A  HEATING  AGENT        .  .       .    275 

CHAPTER  XXVIII 
ELECTRICITY'S  RELATION  TO  HEAT         .  «  280 

CHAPTER  XXIX 

How  ELECTRICITY  AIDS  THE  CONJURER  *  .    287 

CHAPTER  XXX 

How  WE  MEASURE  ELECTRICITY  .  »          •       .    299 

CHAPTER  XXXI 

SOME  QUESTIONS  ANSWERED    .  .  .  .    315 

CHAPER  XXXII 
WHAT  WE  KNOW  ABOUT  ELECTRICITY    .  ...    322 

CHAPTER  XXXIII 
CONCLUSION  .  .  .  .  .    331 

INDEX  .  .  .  .  .    339 


n 


LIST  OF   ILLUSTRATIONS 

PACK 

PASSENGER  HOIST  ON  THE  WETTERHORN  .          Frontispiece 

THE  UPPER  STATION  ON  THE  WETTERHORN        .  20 

A  MAGNET  AND  A  NEIGHBOURING  ELECTRIC  CURRENT  .       .  42 

SUSPENDED  ELECTRIC  RAILWAY  AT  ELBERFELD  .  50 

FIREMEN  WITH  TELEPHONE  HELMETS     ,              .           .       .  64 

GROWTHS  ON  A  SUBMARINE  CABLE        .              .           .       .  80 

INTERIOR  OF  A  WIRELESS  TELEGRAPH  STATION  .  94 

A  FLASH  OF  LIGHTNING  PHOTOGRAPHED             .                  .  106 

LARGE  ELECTRO-MAGNET  LIFTING  A  THREE-TON  CASTING      .  128 

A  MODERN  TELEPHONE  EXCHANGE  SWITCH-ROOM          .        .  146 

AUTOMATIC  TELEPHONE  INSTRUMENTS    .              .                  .  152 

CHINESE  BOYS  AT  WORK  IN  SHANGHAI  TELEPHONE  EXCHANGE  174 

A  MINIATURE  ELECTRIC  MOTOR-CAR       *              .           .       .  188 

SPINNING  MILL  ELECTRICALLY  DRIVEN  .              ...  204 

PORTABLE  ELECTRIC  DRILL  AT  WORK  ON  SHIP'S  STERN  .       .210 

CANAL  HAULAGE  BY  ELECTRIC  TRACTOR             .          .       .  218 

INTERIOR  OF  NIAGARA  POWER  STATION               ,           .       .  222 
X-RAY    PICTURES  :    (i)    MUMMY'S    FEET  ;    (ii)    LORD    HUGH 

CECIL'S  HAND       .              .              .              ...  236 

ELECTRIC  LOCOMOTIVE  AND  TRUCKS      .             .          .       .  252 

(i)  HIGH-SPEED  TRAIN  ;  (ii)  ELECTRIC  RAILWAY  IN  A  MINE   .  264 

ELECTRIC  COAL-CUTTER  AT  WORK          .              .           .        .  270 

AMERICAN  ELECTRIC  ORE  LOADER         .             ...  284 

ELECTRIC  SHOCK-PROOF  OVERALL          .              ...  300 

A  CORNER  OF  THE  AUTHOR'S  LABORATORY         .          .       .  326 

'3 


LIST   OF   DIAGRAMS 

PAGE 

FIG.    i;    THE  EARLIEST  ELECTRIC  BATTERY        .  29 

,,     2.    VOLTA'S  BATTERY  OF  CELLS    .              .  29 

,,     3.    SIGNALS  FOR  NEEDLE  TELEGRAPH         .  55 

,,     4.    SIGNALS  FOR  MORSE  TELEGRAPH          .  57 

,,     5.    SHOWING  A   CELL   CONNECTED  TO   A   TELEGRAPH 

INSTRUMENT           .              .              ...  60 

,,     6.    How  A  TELEGRAPH  is  WORKED  WITH  A  SINGLE 

WIRE        .              .              .                                 .  61 

,,     7.    THE  CABLE  ALPHABET             .              .  82 

,,     8.    THE  PRINCIPLE  OF  WIRELESS  TELEGRAPHY     .        .  97 
„     9.    THE  PRINCIPLE  OF  THE  TELEPHONE      .           .        .143 

„    10.    THE  PRINCIPLE  OF  INDUCTION  COILS    .           .        .  168 

,,    ii.    A  SIMPLE  FORM  OF  X-RAY  TUBE           .           .        .  181 

,,    12.    THE  PRINCIPLE  OF  A  CONTINUOUS-CURRENT  DYNAMO  195 

,,    13.    THE  PRINCIPLE  OF  A  DYNAMO  SUPPLYING  ALTER- 
NATING CURRENT                                         .       .  202 


THE  KOMANCE  OF 
MODERN  ELECTRICITY 


CHAPTER  I 

THE  PART   PLAYED  BY 
ELECTRICITY 

A  seeming  lack  of  interest  which  is  not  real— The  character  of 
electricity — Mystery  concerning  the  nature  of  electricity — 
Lightning — Some  of  electricity's  manifold  duties. 

MANY  people  believe  honestly  that  a  knowledge  of 
electrical  matters  is  beyond  their  reach.     Some 
years  ago  I  got  into  conversation  with  the  post- 
master in  a  little  country  village.     Finding  that  he  had 
no  conception  whatever  of  the  way  in  which  his  telegraph 
instrument  worked,  I  explained  it  to  him  in  a  few  words. 
It  was  amusing  to  see  his  surprise ;  he  had  supposed  that 
to  know  such  things  required  a  "  second  edication." 

It  has  always  been  a  matter  of  wonderment  to  me  how 
so  many  people  are  content  to  pass  through  life  taking 
advantage  of  all  the  modern  applications  of  electricity 
and  yet  apparently  indifferent  to  the  means  by  which 
those  modern  marvels  are  worked.  As  indicated  in  the 
opening  sentence,  however,  much  of  this  seeming  lack  of 
interest  has  been  due  to  a  misapprehension,  And  from 

15 


THE   NATURE  OF   ELECTRICITY 


tjhte  '^thftsidstict  reception  accorded  to  the  earlier  editions 
of  this  present  "Romance,"  it  is  quite  evident  that  the 
general  reader  is  genuinely  interested  in  the  subject  of 
electricity. 

There  is  no  gainsaying  the  fact  that  much  relating  to 
the  nature  of  electricity  is  shrouded  in  mystery,  but  that 
does  not  mean  that  there  is  any  mystery  concerning  the 
working  of  telegraphs,  telephones,  electric  motors,  dyna- 
mos, and  all  the  other  practical  applications  of  electricity. 

By  pointing  to  the  falling  weights  in  a  grandfather 
clock,  it  is  not  difficult  to  let  a  child  understand  how  the 
wheels  go  round.  But  the  most  learned  scientist  has  no 
definite  idea  of  the  nature  of  the  force  which  causes  the 
weights  to  fall.  It  is  not  recognised  by  many  that  our 
ideas  concerning  the  nature  of  electricity  are  much  more 
definite  than  those  regarding  gravitation.  However,  it  is 
evident  that  we  can  proceed  to  consider  how  electricity  is 
applied  without  waiting  to  discuss  the  present  ideas 
concerning  its  nature.  After  we  have  become  familiar 
with  electricity  at  work,  it  will  be  of  interest  to  see  how 
far  we  have  unravelled  the  mystery  of  its  nature. 

No  doubt  many  readers  have  some  sort  of  nodding 
acquaintance  with  electrical  appliances.  In  any  case,  we 
are  all  familiar  with  the  telephone,  and  we  have,  no 
doubt,  seen  some  form  of  electric  telegraph  instrument. 
Those  who  have  made  no  study  of  such  instruments  have 
doubtless  surrounded  them  with  an  atmosphere  of  mystery. 
To  any  one  who  cares  to  consider  the  matter  seriously  it 
must  be  clear  that  all  such  instruments  are  made  of 
pieces  of  ordinary  metal,  wood,  glass,  and  such  like. 
There  is  no  mystery  about  the  apparatus.  The  dynamos 

16 


THE   NATURE    OF   ELECTRICITY 

which  are  supplying  the  electric  current  for  lighting  a 
whole  city  are  merely  collections  of  pieces  of  iron  and 
brass,  and  bundles  of  wires. 

Perhaps  our  earliest  recollections  of  electricity  are  in 
connection  with  Nature's  grand  display.  We  have  child- 
hood memories  of  those  huge  electric  sparks  which  we 
call  lightning.  These  great  electrical  demonstrations  have 
been  known  to  men  of  the  remotest  ages ;  indeed,  we  are 
safe  in  saying  that  there  were  lightnings  and  thunders 
before  man  was  created.  We  shall  see  later  that  the 
ancients  failed  to  recognise  the  nature  and  origin  of  the 
lightning.  But  what  I  wish  to  point  out  at  present  is 
the  fact  that  electricity  is  as  old  as  the  world  itself. 
Sometimes  one  hears  people  speak  of  electricity  as  though 
it  were  an  invention  of  modern  man.  It  is  true  that 
only  in  modern  times  has  electricity  been  harnessed  and 
made  to  do  useful  work,  but  all  the  electricity  which  we 
can  call  to  our  service  to-day  has  been  in  existence,  in  some 
available  form,  from  the  beginning  of  this  world. 

It  is  of  interest  to  notice  the  nature  of  the  part  played 
by  electricity.  Electricity  is  in  reality  a  go-between. 
For  instance,  if  we  pay  a  visit  to  the  power-house  which 
supplies  electricity  for  driving  the  tramway  cars  in  a  great 
city,  we  see  much  evidence  of  energy.  There  is  the 
immense  heat  energy  of  the  great  furnaces,  producing 
the  necessary  steam  pressure  to  drive  huge  engines.  In 
the  going  parts  of  the  great  engines  we  get  some  idea 
of  the  vast  amount  of  energy  which  is  being  used.  We 
see  these  engines  driving  large  dynamos,  but  after  this 
we  lose  sight  of  all  evidence  of  the  energy.  It  has  been 
handed  on  to  the  care  of  the  invisible  go-between,  which 

we  call  electricity. 

B  17 

I 


ELECTRICITY'S    MANIFOLD    DUTIES 

The  invisible  electric  current  is  now  the  means  of 
carrying  the  energy  out  to  the  distant  tramway  cars. 
There  it  enters  the  electric  motors  which  are  beneath 
the  cars  and  causes  the  wheels  to  turn  round.  As  we 
watch  the  tramway  car,  with  fifty  people  on  its  back, 
climb  a  steep  hill,  we  see  once  more  that  the  energy 
which  left  the  great  power-house  has  not  been  lost.  We 
shall  understand  later  how  the  dynamos  and  motors 
work ;  for  the  present  we  wish  to  realise  that  electricity 
is  a  most  helpful  go-between. 

Our  object  in  the  present  volume  is  to  see  how 
electricity  has  been  harnessed  to  assist  us  in  our  every- 
day life.  We  have  noted  already  its  application  in 
transmitting  energy  to  a  distance.  We  shall  see  also 
the  means  by  which  it  produces  that  most  convenient  of 
all  forms  of  artificial  light. 

It  will  be  of  interest  also  to  see  how  electricity  has 
enabled  man,  by  means  of  the  electric  telegraph,  to 
communicate  with  his  fellow-men  in  every  civilised  part 
of  this  great  planet.  Then  again  it  seems  almost  in- 
credible that  we  can  telegraph  to  ships  far  out  on  the 
ocean,  even  when  we  do  not  know  their  exact  where- 
abouts. Yet  we  shall  see  that  the  methods  of  doing  so 
are  easily  understood. 

Perhaps  we  have  ceased  to  marvel  at  the  fact  that  a 
man  in  London  can  carry  on  ordinary  conversation  with  a 
friend  in  Paris,  or  in  the  distant  capital  of  Scotland. 
When  we  come  to  consider  the  means  by  which  this  is 
accomplished  we  cannot  fail  to  be  interested. 

The  fact  that  we  can  now  speak  over  a  great  distance 
through  space,  without  the  aid  of  any  connecting  wires, 

itf 


ELECTRICITY'S    MANIFOLD    DUTIES 

is  one  of  the  latest  practical  achievements  in  the  electrical 
world. 

Electricity  has  proved  a  most  helpful  handmaiden 
to  Chemistry  in  the  industrial  world.  In  addition  to 
the  practical  side  of  the  subject,  we  shall  see  that 
all  chemical  actions  are  in  reality  due  to  electrical 
activities  between  the  particles  of  which  all  substances 
are  composed. 

In  many  other  directions  we  shall  find  electricity 
coming  to  man's  aid.  To  mention  only  one  other  practical 
application,  we  might  select  the  means  of  producing 
Rontgen  raysj  which  have  proved  of  the  greatest  possible 
assistance  to  the  physician.  We  shall  have  no  difficulty 
in  seeing  how  electricity  works  all  these  modern  marvels. 

While  the  title  of  this  volume  is  "The  Romance  of 
Modern  Electricity,"  it  will  be  of  interest  to  see  what 
little  the  ancients  did  know  of  this  great  agent. 
Although  this  takes  our  story  back  several  thousand 
years,  we  shall  see  that  all  the  practical  applications  of 
electricity  are  very  modern.  Indeed,  most  of  the  ad- 
vances which  electricity  has  made  into  our  everyday  life 
have  taken  place  within  the  personal  recollection  of  very 
many  of  us. 

Those  of  us  who  can  compare  the  condition  of  electrical 
undertakings  of  to-day  with  those  which  existed  twenty- 
five  years  ago,  are  forced  to  wonder  what  further  ad- 
vances may  be  made  during  the  next  twenty-five  years. 
However,  it  will  be  of  interest  to  us  to  commence  the 
story  at  the  beginning,  and  consider  how  we  came  to 
know  about  electricity. 


CHAPTER  II 

HOW  WE    CAME   TO   KNOW  ABOUT 
ELECTRICITY 

Early  magic  in  the  East— The  Chinese  discover  a  peculiar  stone  which 
guides  them  across  the  deserts— Peculiar  property  possessed  by 
amber— One  of  Queen  Elizabeth's  physicians  makes  important 
discoveries— The  earliest  electrical  machines— A  modern  giant 
machine— The  present  use  of  such  apparatus. 

THOUSANDS  of  generations  of  men  spent  their  lives 
upon  this  planet  without  acquiring  any  knowledge 
of  this  wonderful  agent  which  we  call  electricity. 
King  Solomon  declared  that  there  is  nothing  new  under 
the  sun  ;  electricity  is  not  a  new  thing.     All  the  electricity, 
all  the  matter,  and   all  the  energy  which  exist  to-day 
have  existed  from  the  beginning  of  the  world. 

Of  course  it  may  be  that  the  ancient  wise  men  of  the 
East  knew  much  more  of  this  subject  than  we  give  them 
credit  for.  It  is  very  probable  that  electric  and  magnetic 
phenomena  formed  the  basis  of  much  of  the  magie  of 
these  early  times ;  and  some  writers  have  even  suggested 
that  Tullus  Hostilius,  instead  of  being  "struck  down 
dead  by  a  thunderbolt  from  Jove  for  practising  magical 
arts,"  was  more  prosaically  robbed  of  life  by  being  the 
recipient  of  a  fatal  electric  shock.  This  would  certainly 
have  been  possible  had  Tullus  Hostilius  been  experiment- 
ing after  the  fashion  of  Franklin  and  others  in  a  thunder- 

20 


By  permission  oj 


serei  Bern,  Switzerland 


THE  UPPER  STATION  ON  THE  WETTERHORN 

To  realize  the  height  at  which  this  station  is,  one  must  refer  to  the  frontispiece. 
When  the  cars  are  nearing  a  stopping- place  they  automatically  switch  off  the 
electric  current,  and  should  any  accident  occur  to  the  car  or  the  cable  a  magnetic 
brake  comes  into  action  and  stops  the  car  immediately. 


A  PECULIAR  STONE 

storm.  Be  that  as  it  may,  we  should  be  able  to  find 
sufficient  interest  among  the  actual  facts  recorded. 

To  trace  how  man  came  to  know  about  electricity  one 
has  to  go  back  to  a  date  at  least  one  thousand  years 
before  Christ.  It  is  recorded  that  at  this  early  date  the 
Chinese  were  in  possession  of  a  certain  kind  of  stone 
which,  when  supported  in  the  outstretched  arm  of  a  little 
revolving  figure  on  their  caravans,  guided  them  across  the 
trackless  wastes  of  Tartary.  Exactly  how  and  when  they 
discovered  the  peculiar  property  of  this  stone  is  not 
known,  but  we  must  reckon  this  discovery  as  a  definite 
starting-point  in  our  knowledge  of  electricity.  Some 
authorities  claim  that  this  stone,  which  was  christened 
lodestone  (leading-stone),  was  known  as  early  as  2600  B.C. 
It  is  a  class  of  iron  ore,  presumably  magnetised  by  the 
earth's  influence,  and  is  found  in  many  parts  of  the  world. 

No  doubt  the  ancients  would  first  observe  that  this 
lodestone  attracted  small  pieces  of  iron,  and  that  these 
held  on  to  it  with  a  tenacity  that  might  have  suggested 
the  presence  of  life,  which  phenomenon  would  doubtless 
be  quite  satisfactorily  explained  in  those  days  by  admitting 
that  the  stone  had  a  soul. 

This  stone  would  be  a  wonder  to  the  wise  men,  and 
many  would  gain  possession  of  a  specimen,  so  that  it 
would  not  be  long  before  someone  observed  that  when  a 
piece  of  this  material  was  freely  suspended,  it  always 
came  to  rest  in  a  certain  definite  position,  which  from 
observation  turned  out  to  be  with  one  end  pointing  north 
and  the  other  end  pointing  south. 

It  was  a  further  step  in  advance  when  it  was  found 
that  this  lodestone  was  able  to  impart  its  own  peculiar 

11 


AN  IMPORTANT  DISCOVERY 

properties  to  a  piece  of  iron  in  contact  with  it,  and  that 
when  the  stone  was  repeatedly  drawn  along  a  piece  of 
hard  iron  the  latter  came  to  possess  these  properties  in 
some  degree  on  its  own  account,  and  without  any  loss 
of  power  to  the  lodestone.  Such  pieces  of  iron  were 
called  magnets,  this  word  probably  being  derived  from 
Magnesia,  a  place  in  Asia  Minor,  where  the  lodestone  was 
obtained  in  some  quantity. 

Another  phenomenon  was  observed  in  those  early  days, 
which  is  recorded  by  a  Greek  philosopher  as  far  back  as 
600  B.C.,  but  which  until  modern  times  was  not  supposed 
to  have  any  connection  with  the  lodestone  phenomena. 
It  was  found  that  when  a  piece  of  amber  (a  mineralised 
resin  of  extinct  pine  trees)  was  rubbed,  it  would  attract 
any  light  bodies  towards  itself,  as  for  instance,  pieces  of 
straw,  paper,  etc.  The  schoolboy  may  repeat  this  old- 
world  experiment  by  simply  rubbing  a  piece  of  sealing- 
wax  upon  his  coat-sleeve.  Of  course,  it  is  evident  that 
this  attractive  property  is  not  the  same  as  that  of  the 
lodestone,  which  will  attract  only  iron,  while  the  rubbed 
amber  is  able  to  attract  any  light  body.  However,  we 
shall  not  have  gone  far  before  we  see  the  very  intimate 
connection  which  exists  between  these  two  apparently 
different  phenomena. 

Man's  further  knowledge  of  these  phenomena  seems  to 
have  made  no  progress  until  one  of  Queen  Elizabeth's 
physicians  made  a  special  study  of  the  properties  of  lode- 
stone  and  rubbed  amber,  and  he  got  so  far  ahead  of  the 
knowledge  of  his  time  (1600  A.D.)  that  practically  no- 
thing of  importance  was  added  till  the  close  of  the 
eighteenth  century. 

22 


EARLIEST  ELECTRICAL  MACHINES 

This  great  genius,  Dr.  Gilbert,  of  Colchester,  dis- 
coveied  that  the  old-world  phenomenon  of  attraction  did 
not  belong  only  to  amber,  but  that  a  great  number  of 
things  acted  in  the  same  way  when  rubbed.  More  than 
a  century  passed  before  it  was  found  that  all  bodies,  if 
certain  conditions  were  observed,  would  exhibit  this 
property  of  attraction.  By  briskly  rubbing  a  piece  of 
well-dried  brown-paper  with  an  ordinary  clothes-brush, 
I  have  succeeded  in  getting  the  paper  to  exhibit  electrical 
attraction.  Of  course  some  bodies  act  very  much  better 
than  others,  and  so  it  has  been  found  by  experiment  that 
a  piece  of  vulcanite  rubbed  with  a  cat's  skin,  or  a  glass 
rod  "  excited "  by  a  piece  of  silk  cloth,  give  the  best 
results  obtainable  by  simply  rubbing  them  together. 

Our  word  "electricity"  is  a  fitting  memorial  of  the 
ancient  amber  experiment,  as  it  is  derived  from  the  Greek 
word  rj\eKTpov  (electron)  signifying  amber. 

After  Dr.  Gilbert's  discovery  became  known,  people  set 
about  making  machines  to  do  the  rubbing  for  them  on 
a  larger  scale.  The  earliest  of  these  machines  consisted 
merely  of  a  large  sulphur  ball  rotated  on  a  spindle,  while 
the  experimenter  used  his  hand  as  the  rubber  by  holding 
it  against  the  revolving  ball.  Glass  cylinders  soon  re- 
placed the  sulphur  ball,  and  even  with  such  primitive 
apparatus  an  electric  spark  was  produced.  It  was  also 
found  that  if  two  bodies  were  similarly  electrified  by 
touching  the  excited  glass  cylinder,  these  two  bodies  when 
brought  near  to  each  other  repelled  one  another,  while 
each  continued  to  attract  any  other  light  body. 

Working  with  this  same  simple  apparatus,  in  the  early 
part  of  the  eighteenth  century,  it  was  found  that  this 

23 


A  MODERN   GIANT  MACHINE 

electrical  influence  could  be  transmitted  along  a  number 
of  pack  threads  (suspended  by  silk  threads)  to  a  distance 
of  about  300  yards ;  and  a  few  years  later  it  was  observed 
that  when  the  pack  threads  were  wetted  the  distance 
might  be  increased  to  over  400  yards. 

It  was  only  natural  that  improvements  should  be  added 
to  these  early  machines  from  time  to  time,  and  the  first 
step  in  this  direction  was  the  introduction  of  a  leather 
cushion,  to  act  as  the  rubber  in  place  of  the  experimenter's 
hand.  Then  suitable  means  were  devised  for  collecting 
the  electrical  influence  from  the  machine.  In  modern 
"  influence "  or  "  statical "  machines  there  is  no  actual 
rubbing.  Two  glass  or  vulcanite  plates,  each  carrying 
a  series  of  small  slips  of  thin  metal  foil  upon  them,  are 
made  to  revolve  close  to  each  other  in  opposite  directions, 
and  by  a  process  known  as  "induction,"  an  electrical 
charge  is  induced  on  the  plates  and  suitably  collected. 
If  a  number  of  pairs  of  plates  are  used  a  very  big  electri- 
cal effect  may  be  produced.  The  late  Lord  Blythswood 
constructed  in  his  private  laboratory  an  immense  electrical 
machine,  having  160  plates,  each  measuring  three  feet  in 
diameter,  and  it  would  be  no  pleasure  for  a  person  of 
nervous  temperament  to  be  in  the  immediate  neighbour- 
hood of  this  machine  while  it  discharges  lightning  flashes 
with  an  almost  deafening  report. 

Some  modern  electrical  machines  have  been  made  using 
plain  vulcanite  plates  without  any  metal  foil,  and  these 
have  been  found  to  give  excellent  results. 

All  these  electrical  machines  are  of  scientific  as  well  as 
historical  interest,  but  they  do  not  enter  into  the  com- 
mercial applications  of  electricity.  They  produce  what 

24 


USE  OF  SUCH   APPARATUS 

we  call  an  electrical  discharge,  and  not  the  useful  electric 
current  of  which  we  shall  hear  so  much  in  the  following 
pages. 

If  these  electrical  machines  had  remained  our  only 
means  of  supplying  electrical  energy,  we  should  never 
have  had  any  practical  form  of  electric  telegraph,  the 
telephone  would  have  been  impossible,  while  electric  light 
and  electric  motors  would  have  remained  unknown. 

The  first  practical  step  was  the  invention  of  electric 
batteries ;  it  will  be  of  interest  to  see  how  this  came 
about. 


CHAPTER  III 
HOW  BATTERIES  WERE   INVENTED 

What  the  twitching  of  a  frog's  legs  led  to— A  debt  we  owe  to  two 
Italian  professors— The  meaning  of  electric  pressure— Can  we 
store  electricity  ?— Some  early  experimenters  have  an  alarming 
experience— The  true  meaning  of  conductors  and  insulators. 

WE  have   become   so   accustomed  to   the   use  of 
electric  batteries   that  people  seldom  stop  to 
ask  how  it  was  that  the  principle  of  these  was 
first  discovered. 

The  story  is  a  very  simple  and  interesting  one.  A 
little  more  than  a  century  ago  an  Italian  physician, 
Professor  Galvani,  made  a  series  of  experiments  with  one 
of  those  early  electrical  machines,  such  as  described  in  the 
preceding  chapter.  He  was  studying  the  effect  of  an 
electric  charge  upon  animal  structures,  and  while  experi- 
menting he  observed  that  the  legs  of  a  freshly  killed  frog 
were  convulsed  if  they  were  placed  near  to  the  discharge 
of  an  electrical  machine.  Some  writers  believe  this  dis- 
covery to  have  been  purely  accidental,  and  they  relate  the 
story  how  some  edible  frogs  had  been  skinned  to  make 
soup  for  Madame  Galvani,  who  was  an  invalid,  and  that 
these  frogs  happened  to  be  lying  in  the  Professor's  labora- 
tory when  he  first  observed  this  peculiar  twitching.  One 

26 


THE  TWITCHING  OF  A  FROG'S  LEG 

would  not  expect  to  find  frogs,  partially  prepared  for 
food,  to  be  left  lying  about  an  experimental  laboratory, 
especially  when  the  master  of  the  house  was  a  doctor.  It 
is  more  reasonable  to  suppose  that  Galvani,  who  was  a 
professor  of  anatomy,  would  be  purposely  trying  the 
effect  of  these  discharges  upon  a  lifeless  frog.  Be  that  as 
it  may,  there  is  no  doubt  that,  after  having  once  observed 
these  convulsive  kicks,  he  would  proceed  with  further 
experiments,  so  that  the  next  part  of  the  story  seems 
quite  probable.  Having  passed  a  copper  skewer  through 
the  limbs  of  a  frog,  Galvani  was  about  to  hang  these  up 
on  an  iron  rail  when,  as  soon  as  the  copper  touched  the 
iron,  he  noticed  the  same  convulsive  twitching  which  he 
had  previously  observed  to  be  due  to  the  discharge  of  an 
electrical  machine.  A  few  further  trials  and  Galvani 
would  find  that  this  phenomenon  could  be  repeated  at 
will.  It  was  soon  found  that  the  best  effect  was  obtained 
by  touching  a  nerve  in  the  frog's  limb  with  a  piece  of 
zinc  and  a  muscle  with  a  piece  of  copper,  and  then  as 
soon  as  the  two  free  ends  of  the  metals  were  brought 
together  the  convulsive  kick  took  place,  just  as  though 
the  frog's  legs  had  come  back  to  life. 

Galvani  failed  to  give  a  correct  explanation  of  the 
cause  of  this  phenomenon.  He  attributed  the  twitching 
movement  to  electricity  generated  by  the  animal  tissue 
itself,  but  the  correct  solution  was  suggested  by  another 
Italian  professor  (Volta).  He  maintained  that  the  elec- 
tricity was  not  in  the  animal,  but  was  due  to  the  contact 
of  the  two  different  metals  being  in  touch  also  with  the 
moist  flesh.  Volta  was  soon  able  to  prove  his  assertion 
by  making  up  a  battery  of  pieces  of  dissimilar  metals. 


THE  TWITCHING  OF  A  FROG'S  LEG 

The  word  battery  is  here  used  in  the  same  sense  as  one 
speaks  of  a  battery  of  guns.  Taking  a  number  of  discs  of 
zinc  and  the  same  number  of  copper  discs,  Volta  placed 
these  in  pairs  of  one  copper  and  one  zinc,  each  pair  being 
separated  from  its  neighbour  pair  by  a  wafer  of  cloth 
moistened  with  acidulated  water.  When  the  topmost  zinc 
was  brought  into  metallic  contact  with  the  bottom  copper 
disc,  by  joining  these  together  with  a  wire  it  was  found 
that  a  continuous  current  of  electricity  was  set  up  in  the 
wire  (see  Fig.  1).* 

Volta  was  able  with  his  pile  of  discs  to  show  an  electric 
spark,  but  believing  that  he  might  still  increase  the  effect, 
he  placed  each  pair  of  discs  in  a  separate  vessel  filled  with 
acidulated  water,  instead  of  merely  dividing  them  by  a 
moist  cloth.  When  these  different  couples  were  connected 
up  as  in  Fig.  £,  a  very  enhanced  effect  was  produced. 
This  second  arrangement  went  by  the  name  of  "Volta's 
cells,""  and  the  diagram  (Fig.  2)  represents  several  cells 
coupled  together,  forming  a  "battery"  of  cells.  It  has 
become  general  to  speak  of  one  cell  as  a  battery,  but  we 
have  no  more  right  to  do  so  than  to  call  one  gun  a 
battery  of  guns.  One  very  often  hears  people  speak  of  a 
galvanic  battery,  but  it  would  be  more  appropriate  to  say 
a  voltaic  battery,  for  Galvani  had  no  part  in  the  sugges- 
tion of  the  chemical  cell  or  battery,  which  is  due  entirely 
to  Volta.  It  was,  of  course,  Galvani's  frog  experiment 
that  led  Volta  to  make  investigations  which  ultimately 

*  It  was  found  later  that  the  active  pair  of  discs  was  not  the  pair 
in  contact  with  each  other,  but  that  the  chemical  action  giving  rise  to 
the  electric  current  was  between  the  zinc  and  copper  disc  which  were 
separated  by  the  moist  cloth.  Therefore  if  the  topmost  zinc  disc 
(see  diagram)  and  the  lowest  copper  disc  were  removed,  the  electrical 
effect  would  remain  the  same. 


FIG.  1 

THE  EAHLIEST  ELECTRIC   BATTERY 


FlO.    2 

VOLTA'S  BATTERY  or  CELLS 


A  DEBT  WE   OWE 

resulted  in  the  voltaic  cell,  but  Galvani  was  on  quite  the 
wrong  track  as  regards  the  meaning  of  the  frog  experi- 
ment. 

Surely  we  owe  a  great  deal  to  both  Galvani  and  Volta, 
for  it  is  as  though  they  had  tamed  the  wild  and  fiery 
electricity  of  earlier  times  and  made  it  behave  in  a  more 
tractable  manner. 

The  chemical  cell  or  "  battery  "  of  the  present  day  is 
very  similar  to  Volta's  earliest  form.  One  battery  in  very 
general  use  consists  of  a  piece  of  carbon  and  a  piece  of 
zinc  immersed  together  in  a  glass  jar  containing  a  solu- 
tion made  by  dissolving  some  sal-ammoniac  (ammonium 
chloride)  in  water. 

One  finds  very  little  variation  in  the  size  of  these  cells, 
and  the  reason  is  that  no  matter  how  large  any  particular 
cell  is  made,  the  electric  pressure  is  always  the  same.  The 
pressure  or,  as  it  is  termed,  the  electro-motive  force 
(E.M.F.)  of  a  cell  varies  somewhat  according  to  the  metals 
and  chemicals  used,  but  it  is  invariably  between  one  and 
two  volts — the  volt  being  the  unit  of  pressure,  as  will  be 
explained  later.  If  we  made  a  cell  as  large  as  the  ocean 
we  should  still  find  the  same  low  voltage.  We  should  have 
an  increased  quantity  at  hand ;  but,  without  an  efficient 
pressure  to  drive  it  through  any  resistance  we  put  in  its 
path,  it  would  be  of  very  little  use  for  any  practical  pur- 
pose. We  might  have  an  immense  reservoir  of  water 
harnessed  to  a  water-wheel,  but  if  the  reservoir  was  situ- 
ated at  sea-level  it  would  have  no  available  pressure,  and 
we  could  not  get  the  water  to  do  useful  work.  If  we  take 
a  number  of  cells  and  form  a  battery  by  coupling  together 
all  the  zincs  and  then  all  the  carbons,  we  have  still  the 

30 


MEANING  OF  ELECTRIC  PRESSURE 

same  result  as  far  as  pressure  is  concerned,  for  it  is  just  as 
though  we  had  one  large  cell ;  but  if  we  couple  the  cells 
together,  connecting  the  zinc  of  one  cell  with  the  carbon 
of  the  next,  then  we  get  the  added  pressures  of  all  the 
cells.  If  we  take  four  cells  of  two  volts  each  and  couple 
them  as  just  described  "  in  series,"  we  obtain  a  pressure  of 
about  eight  volts. 

This  question  of  connecting  cells  for  pressure  or  for 
quantity  is  so  often  a  stumbling-block  that  I  have  en- 
deavoured to  find  some  more  expressive  way  of  fixing  the 
particulars  in  one's  mind.  If  we  picture  what  takes  place 
in  a  single  cell  the  matter  may  be  clearer.  Owing  to 
chemical  action  in  the  cell  a  current  flows  between  the 
free  ends  of  the  carbon  and  zinc,  and  if  a  wire  join  the  two 
there  will  be  a  flow  of  electricity  from  the  carbon  to  the 
zinc.  If  instead  of  connecting  these  two  elements  of  the 
same  cell  together  we  lead  a  wire  from  the  carbon  of  one 
cell  to  the  zinc  of  the  next,  which  is  in  the  same  condi- 
tion as  the  zinc  of  the  first  cell,  then  we  have  a  pressure 
of  two  volts  from  No.  1  carbon  to  No.  2  zinc,  which  will 
add  on  to  the  pressure  now  produced  in  the  second  cell, 
and  so  on.  We  thus  obtain  about  eight  volts  from  the 
combined  pressures  of  the  four  cells,  but  there  is  a  little 
loss  owing  to  the  power  dissipated  in  overcoming  the 
resistance  offered  to  the  current  by  passing  through 
all  the  cells.  If,  on  the  other  hand,  we  have  the  four 
separate  cells  as  before,  but  connect  all  the  zincs  together, 
the  zincs  will  all  be  in  the  same  electrical  condition. 
Since  the  electromotive  force  is  the  same  in  each  cell  the 
carbons  will  also  be  in  the  same  electrical  condition,  and 
may  be  connected  together.  But  we  gain  nothing  in 

31 


MEANING  OF  ELECTRIC  PRESSURE 

pressure,  the  effect  being  the  same  as  would  be  obtained 
with  a  single  cell  having  a  large  zinc  and  a  large  carbon. 
But  in  this  case  the  four  cells  offer  less  resistance  to  the 
passage  of  the  electric  current  through  them. 

For  almost  all  practical  purposes  we  connect  the  cells 
"  in  series  "  to  get  the  increased  pressure  required  to  over- 
come the  resistance  offered  by  the  apparatus  through 
which  we  wish  to  send  the  current. 

Almost  everyone  now  understands  that  we  cannot 
create  energy,  but  that  we  can  merely  transform  it  from 
one  kind  or  form  of  energy  to  another.  In  our  bodies  we 
transform  the  chemical  energy  of  our  food  into  physical 
energy;  we  supply  the  muscles  with,  what  is  called, 
"  inogen,"  which  gives  them  energy  to  contract  at  our 
will,  and  if  one  mounts  a  bicycle  he  can  get  his  muscles  to 
transform  this  energy  into  a  very  apparent  mechanical 
motion,  and  so  on.  If  we  cease  to  partake  of  food,  we 
soon  use  up  all  the  available  energy,  and  as  this  "inogen" 
is  produced  at  a  certain  rate,  we  may  by  continuous  work- 
ing use  it  up  quicker  than  it  is  being  produced,  in  which 
case  we  feel  a  lack  of  energy,  and  as  soon  as  we  thus 
become  fatigued  we  should  give  our  muscles  rest  to  allow 
time  for  a  further  formation  of  inogen. 

It  is  apparent  that  in  the  battery  it  is  chemical  energy 
which  is  transformed  into  electrical  energy;  and  if  we 
continue  this  process  until  the  chemical  action  ceases,  the 
transformation  will  also  stop,  so  that  it  is  necessary  in 
time  to  add  new  exciting  chemicals. 

These  batteries  of  cells  are  called  primary  batteries,  as 
also  are  the  "dry  cells,"  which  are  now  so  much  in  de- 
mand. The  principle  of  these  dry  cells  is  just  the  same 

32 


MEANING  OF  ELECTRIC  PRESSURE 

as  in  the  simple  cell  already  described,  but  the  liquid  is 
replaced  by  a  moist  paste  for  convenience  of  handling. 

This  seems  a  convenient  opportunity  of  mentioning 
"  secondary "  batteries,  more  commonly  called  storage 
batteries  or  accumulators.  A  secondary  cell  may  consist 
of  two  leaden  plates  perforated  with  holes  which  are  filled 
in  with  red  lead  and  immersed  in  dilute  sulphuric  acid. 
There  is  no  chemical  action  between  these  two  similar 
plates,  so  that  we  cannot  call  forth  any  electrical  energy 
as  we  do  from  a  primary  cell.  If,  however,  a  current  of 
electricity  from  another  source  is  passed  through  this 
secondary  cell,  the  chemical  condition  of  the  plates  is 
found  to  be  entirely  changed,  and  strange  to  say,  the 
change  in  each  plate  has  been  different.  At  the  one 
plate  peroxide  of  lead  is  formed,  while  at  the  other 
spongy  lead  is  observed.  It  almost  seems  like  a  fairy 
tale  to  learn  that  when  these  two  plates  are  now  con- 
nected to  each  other  by  a  wire  the  electricity  appears  to 
return  from  one  plate  to  the  other  in  the  opposite  direc- 
tion to  which  it  was  passed  through  the  cell,  producing  a 
steady  electric  current  in  the  wire  circuit.  On  further 
consideration  it  may  seem  less  wonderful  than  the  simple 
primary  cell  before  described,  for  we  have  in  this  second- 
ary cell  merely  made,  as  it  were,  an  artificial  primary 
cell. 

In  charging  the  secondary  cell  or  accumulator,  we  have 
transformed  electrical  energy  into  chemical  energy,  which 
latter  is  really  what  we  have  stored,  and  which,  as  soon 
as  the  plates  are  connected  by  a  wire,  is  again  trans- 
formed into  electrical  energy.  This  can  hardly  be  called 
storing  electricity.  As  soon  as  the  plates  have  worked 
c  33 


CAN   WE   STORE  ELECTRICITY? 

back  to  their  normal  condition  they  become  inert,  but 
they  may  be  recharged  and  so  on. 

I  think  a  good  analogy  may  be  found  in  the  simple 
principle  of  the  "old  grandfather's  clock."  When  the 
clock  is  standing  with  its  weights  at  the  bottom  and  show- 
ing no  signs  of  energy,  it  is  analogous  to  the  secondary 
cell  uncharged.  The  weights  are  then  raised  against  the 
pull  of  gravity,  and  some  physical  energy  is  expended  by 
the  person  thus  winding  up  the  clock.  In  the  other  pic- 
ture this  is  equivalent  to  the  charging  of  the  cell,  the 
electrical  source  disturbing  the  chemical  conditions  of 
the  plates.  Further,  the  clock  weights,  when  released,  in 
falling  back  to  zero  drive  the  clockwork,  but  as  soon  as 
they  reach  the  bottom  no  energy  is  available ;  analogous 
to  this  is  the  joining  of  the  plates  by  a  wire  through 
which  a  current  of  electricity  flows  until  the  plates  have 
reached  their  normal  condition,  when  no  further  available 
energy  remains  to  be  transformed.  As  already  remarked, 
it  is  chemical  energy  that  is  stored  in  these  accumulators, 
so  that  we  can  only  speak  of  storing  electricity  indirectly. 

Can  electricity  be  stored?  This  question  naturally 
arose  in  the  minds  of  even  the  earliest  experimenters. 
These  men  were  getting  certain  effects  from  their  "rub- 
bing'1 machines,  and  it  was  reasonable  to  suppose  that  if 
they  could  only  store  up  a  quantity  of  electricity  they 
would  get  a  greater  effect.  It  had  been  discovered  that 
glass  offered  a  very  great  resistance  to  the  passage  of 
electricity,  so  it  was  suggested  to  try  and  charge  some 
water  in  a  glass  jar,  and  thus  prevent  the  accumulated 
electricity  from  escaping.  Several  experimenters  appear 
to  have  been  at  work  in  this  direction  at  the  one  time, 

34 


CONDUCTORS  AND  INSULATORS 

and  in  the  University  of  Leyden  (Netherlands),  while  this 
experiment  was  being  carried  out,  quite  an  alarming 
incident  occurred.  The  water  having  been  charged,  the 
person  holding  the  glass  jar  very  naturally  took  hold  of 
the  metal  which  had  been  conveying  the  charge  to  the 
water,  in  order  to  disconnect  it  from  the  machine,  but 
whenever  he  touched  this  he  received  a  severe  shock 
through  the  arms  and  breast.  In  this  way  it  was  dis- 
covered that  if  a  conductor  is  charged  inside  a  glass  vessel, 
and  having  another  conductor  outside,  as  soon  as  the  con- 
ductors are  connected  together  there  is  a  sudden  discharge 
of  the  accumulated  electric  strain.  In  the  original  ex- 
periment the  water  formed  the  inside  conductor,  while 
the  experimenter  holding  the  jar  was  the  outside  con- 
ductor, but  "  Leyden  jars  "  were  constructed,  using  a  tin- 
foil coating  both  on  the  inside  and  the  outside  of  the 
glass,  carrying  the  foils  about  half-way  up  the  jar.  A 
metal  connection  on  an  upright  rod  is  placed  inside,  and  it 
is  then  convenient  to  discharge  the  jar  by  a  pair  of  dis- 
charging tongs,  touching  the  outside  tinfoil  with  one 
prong  and  bringing  the  other  near  to  the  metal  upright, 
when  a  vivid  spark  is  seen  at  this  point.  By  having  the 
metal  coatings  of  the  Leyden  jar  removable,  it  may  be 
shown  that  the  electric  strain  is  stored  in  the  glass  and 
not  in  the  metal  coatings. 

It  may  be  of  service  to  remark  at  this  point  that  all 
bodies  will  conduct  electricity,  provided  the  current  has 
sufficient  pressure  to  overcome  the  resistance  offered  to 
its  passage.  The  difference  between  the  conducting  pro- 
perties of  some  materials,  however,  is  as  great  as  is  a 
drop  of  water  to  a  mighty  ocean ;  or  perhaps  a  better 

35 


CONDUCTORS  AND  INSULATORS 

analogy  would  be  to  say  that  while  a  pipe  or  tube  will 
conduct  water,  a  solid  log  of  wood  will  also  do  so,  but  in 
a  very  different  degree.  The  metals  are  very  good  con- 
ductors of  electricity,  silver  and  copper  being  the  best; 
and  being  very  nearly  equally  good,  copper  is,  of  course, 
preferred  for  economy,  and  it  is  this  property  of  copper 
which  has  so  increased  the  demand  for  the  metal  during  the 
last  half-century.  Glass,  india-rubber,  cotton,  and  silk, 
are  all  such  poor  conductors  that  they  have  been 
termed  non-conductors  or  insulators.  Between  the  metals 
and  these  come  some  materials  which  are  neither  good 

D 

conductors  nor  good  insulators;  and  it  must  bo  borne 
in  mind  that  these  terms  are  merely  comparative,  for 
a  substance  might  be  a  conductor  for  one  purpose 
and  an  insulator  for  another.  A  heap  of  sand  may 
be  sufficient  to  stop  a  tiny  streamlet  on  its  way  to 
the  ocean,  but  something  more  would  be  required  to 
stop  the  same  amount  of  water  issuing  under  pressure 
from  the  nozzle  of  a  hose-pipe. 

When  two  bodies  are  said  to  be  put  into  metallic  contact 
with  each  other,  it  simply  means  that  they  are  connected 
together  by  a  wire,  or  other  piece  of  metal,  which  offers  a 
conducting  path  through  which  electricity  may  be  caused 
to  pass  from  the  one  object  to  the  other. 

What  about  the  electric  pressure  of  an  accumulator? 
It  is  the  same  humble  story  of  about  two  volts  per  cell ;  an 
increased  pressure  is  obtained,  just  as  in  the  case  of  the 
primary  battery,  by  connecting  the  plates  of  different 
electrical  conditions  together.  These  secondary  batteries 
are  not  only  of  great  use  as  reservoirs,  but  they  give  a 
uniformly  steady  current,  whereas  the  current  obtainable 

36 


CONDUCTORS  AND  INSULATORS 

from  a  primary  battery  is  very  intermittent,  owing  to 
hydrogen  gas  collecting  on  the  carbon  plates  and  inter- 
fering with  the  passage  of  the  current.  Primary  batteries 
are  all  right  for  electric  bells,  telephones,  etc.,  where  there 
is  not  a  continuous  call  upon  their  energy,  but  the  accumu- 
lator is  necessary  where  a  constant  current  is  desired. 


37 


CHAPTER  IV 
WHAT  IS  MAGNETISM? 

One  magnet's  strange  behaviour  towards  another — How  a  magnet  is 
affected  by  a  neighbouring  electric  current— A  magnet  that  will 
attract  and  let  go  at  will— What  takes  place  in  a  piece  of  iron 
when  magnetised— Experiments  that  go  to  prove  an  interesting 
theory. 

FROM  our  childhood  we  have  all  had  some  know- 
ledge of  magnetism  in  connection  with  the  compass 
needle,  and  no  doubt  many  of  us  gained  further 
knowledge  from  magnetic  toys  presented  to  us  to  enable 
us  to  become  expert  anglers.     In  any  case  it  is  scarcely 
necessary  to  remark  that  a  magnet  attracts  iron,  or  that  a 
light  magnet  balanced  upon  a  pivot  will  have  one  end  or 
"  pole  "  pointing  north  and  the  other  south. 

There  is  a  third  and  a  very  remarkable  property  of 
magnets;  a  simple  one  and  yet  one  that  often  leads  to 
confusion.  Every  magnet  has,  of  course,  a  north  and  a 
south-seeking  end  or  "pole,"  and  these  two  ends  are 
usually  brought  close  together  by  making  the  magnet  in 
a  horse-shoe  form,  in  order  to  have  the  attractive  pull  of 
both  poles  combined.  It  is  more  convenient  for  experi- 
mental purposes  to  make  the  magnet  in  the  form  of  a 
straight  bar,  so  that  the  effect  of  each  pole  may  be 
examined  by  itself.  In  order  to  distinguish  the  poles  it 
is  customary  to  mark  the  north-seeking  pole  with  the 

at 


MAGNET'S   STRANGE   BEHAVIOUR 

letter  N,  or  to  paint  that  end  or  mark  it  in  some  way  so 
that  it  is  quite  easy  to  discern  the  north  pole,  while  the 
plain  end  is,  of  course,  the  south. 

If  the  north  pole  of  a  bar-magnet  be  brought  near  to 
the  north  pole  of  a  magnetic  needle  pivoted  upon  a 
stand,  the  north  pole  of  the  needle  will  fly  away  from  the 
north  pole  of  the  bar-magnet,  but  the  south  pole  will 
come  round  and  be  attracted.  The  south  pole  of  the 
magnet  and  the  south  pole  of  the  needle  will  also  repel 
each  other,  but  the  two  unlike  poles  will  always  attract 
one  another.  This  is  certainly  very  strange — the  poles 
all  look  exactly  alike  and  they  will  all  attract  iron 
equally  well,  but  their  behaviour  towards  each  other  is  so 
different ;  the  norths  will  have  nothing  to  do  with  the 
norths,  the  souths  are  equally  repellent  to  one  another, 
but  a  north  and  a  south  are  always  attractive  to  each 
other. 

It  is  most  important  that  the  true  facts  of  the  case 
should  be  impressed  upon  our  minds.  Many  years  ago 
in  delivering  a  popular  lecture  I  had  demonstrated  these 
simple  facts  experimentally,  and  to  my  way  of  thinking 
the  matter  seemed  quite  clear,  but  when  the  chairman, 
who  was  the  possessor  of  several  university  degrees,  made 
some  remarks  in  proposing  a  vote  of  thanks  I  got  quite 
a  big  surprise.  He  said  that  personally  he  had  gained 
a  great  deal  of  information  from  the  lecture,  and  that 
it  was  remarkable  how  little  outsiders  knew  about  these 
matters ;  he  had  not  even  known  till  then  that  a  magnet 
attracted  iron  with  one  end  and  repelled  it  with  the 
other.  Needless  to  say  the  remark  was  decidedly  dis- 
appointing, but  a  brief  repetition  of  the  experiments 

39 


MAGNET'S   STRANGE   BEHAVIOUR 

served  to  show  that  a  magnet  attracts  iron  equally  well 
with  both  poles,  and  that  the  repulsion  only  takes  place 
between  the  two  similar  poles  of  two  magnets.  I  have 
often  observed  this  misunderstanding  during  conversation, 
and  quite  recently  I  find  the  author  of  a  widely  circulated 
book  going  astray  on  this  same  point. 

If  two  north  poles  repel  each  other,  how,  then,  is  the 
north  pole  of  a  compass  needle  attracted  by  the  north 
pole  of  the  earth  ?  In  point  of  fact  the  end  of  the 
compass  needle  pointing  to  the  north  is  of  opposite 
polarity,  but  it  would  be  confusing  to  call  this  north- 
pointing  end  a  "  south "  pole,  although  the  Chinese  and 
the  French  have  done  so.  We  prefer  to  call  it  the  north- 
seeking  pole,  or,  in  short,  the  north  pole,  but  it  must  be 
remembered  that  the  true  meaning  is  the  north-pointing 
or  seeking  pole.  One  does  not  see  any  magnet  in  the 
modern  mariner's  compass,  as  the  compass  card  itself  is 
pivoted  at  its  centre,  and  has  a  number  of  small  magnets 
fixed  to  its  underside,  so  that  the  card  itself  takes  up  its 
correct  position,  indicating  the  different  cardinal  points. 
In  this  way  there  can  be  no  confusion,  as  was  sometimes 
the  case  previously  when  an  inexperienced  person  could 
not  tell  whether  the  painted  or  the  plain  end  of  the 
needle  was  the  north-seeking  pole. 

If  two  bar-magnets  are  used  together,  having  the  two 
north  poles  and  the  two  south  poles  respectively  touching 
each  other,  then  a  more  powerful  magnet  is  the  result, 
as  one  would  quite  anticipate.  If,  however,  the  relative 
position  of  the  magnets  to  each  other  be  reversed,  so  that 
a  north  pole  and  a  south  pole  lie  in  contact  at  each  end} 
all  trace  of  magnetism  disappears.  One  cannot  now 

40 


MAGNET  AND  ELECTRIC  CURRENT 

even  lift  a  small  iron  nail  with  these  two  magnets,  but 
when  separated  again  they  are  each  just  as  attractive  as 
before.  We  have  almost  ceased  to  wonder  at  this  strange 
fact,  but  it  is  none  the  less  remarkable  for  that,  and  it 
will  be  seen  in  the  subsequent  chapters  that  the  peculiar 
behaviour  of  these  magnetic  poles  to  each  other  is  of  the 
very  greatest  importance  to  us  in  practice. 

While  the  early  experimenters  had  been  able  to  make 
magnets  by  rubbing  pieces  of  iron  with  a  natural  magnet 
or  lodestone,  and  while  they  also  had  observed  a  piece  of 
"rubbed"  amber  attracting  light  bodies  to  it,  there  is 
doubt  if  it  ever  occurred  to  them  that  there  might  be 
any  connection  between  magnetism  and  electricity.  Later 
on  the  idea  did  become  definite,  and  during  the  year  in 
which  our  late  Queen  Victoria  was  born  (1819)  a  Danish 
professor  (Hans  Christian  Oersted)  found  that  a  magnetic 
needle  when  brought  near  to  a  copper  wire  carrying  a 
current  of  electricity  behaved  in  a  strange  fashion.  The 
magnet  found  the  wire  of  more  attraction  than  the  north 
and  south  poles  of  the  earth,  so  that  it  would  no  longer 
act  as  a  compass  needle  while  it  remained  in  the  neigh- 
bourhood of  an  electric  current.  If  the  magnet  is  placed 
above  or  below  the  wire,  the  magnet  will  swing  round 
and  take  up  a  position  at  right  angles  to  the  wire. 
Whether  the  north  pole  of  the  magnet  comes  out  to  the 
right  hand  or  to  the  left  hand  depends  upon  the  direc- 
tion in  which  the  current  is  flowing  in  the  wire. 

In  the  accompanying  photographs  a  magnetic  needle  is 
first  shown  standing  at  rest  in  the  neighbourhood  of  a 
copper  wire  in  which  no  current  is  flowing.  In  the  second 
photograph  the  wire  is  connected  to  the  battery  so  that  a 

41 


MAGNET  AND  ELECTRIC  CURRENT 

current  of  electricity  passes  along  the  wire,  and  the  effect 
of  this  neighbouring  current  is  to  cause  the  magnet  to 
turn  round  and  take  up  a  position  at  right  angles  to  the 
wire.  In  the  photographs  the  little  magnet  has  a  round 
paper  disc  attached  to  each  end  in  order  to  show  its  posi- 
tion more  clearly.* 

For  the  present  it  will  be  sufficient  to  note  that  if  we 
send  the  current  along  the  wire  in  one  direction  the  north 
pole  of  the  needle  swings  out  to  the  right  hand,  and  when 
we  send  the  current  in  the  opposite  direction  the  north 
pole  of  the  needle  turns  out  to  the  left  hand. 

The  needle  and  the  wire  may  be  fixed  in  a  vertical  or 
upright  position,  and  the  result  is  the  same.  If  instead  of 
a  single  wire  passing  above  or  below  the  needle  the  wire 
be  continued  round  and  round  to  form  a  coil,  the  result 
is  greatly  enhanced.  This  exceedingly  strange  attitude  of 
the  magnet  towards  the  electric  current  is  of  immense 
importance  to  us,  as  we  shall  see  later. 

After  this  connection  between  electricity  and  mag- 
netism had  been  discovered,  experimenters  would  natur- 
ally wonder  if  the  current  had  any  effect  upon  iron  that 
had  not  been  magnetised.  Very  soon  a  French  scientist, 
Francois  Arago,  was  able  to  show  that  the  wire  carrying 
an  electric  current  did  affect  small  filings  of  iron.  The 
filings  each  appeared  to  become  a  little  magnet,  and  if  a 

*  In  passing  I  would  commend  this  method  to  any  chance  reader 
who  is  accustomed  to  lecture  in  physics.  I  recently  saw  a  very  beau- 
tiful experiment  in  one  of  our  Universities  completely  spoilt  owing  to 
a  lever  being  so  fine  that  its  movements  could  not  be  seen  at  any 
distance.  A  small  disc  cut  from  light  tissue  paper  would  not  have 
hampered  the  movement  of  the  lever,  and  would  have  enabled  the 
audience  to  follow  its  eccentricities  with  ease. 


5  g=  g 
&^  a  « 

U 


•1  I 


a  e 


A  USEFUL   KIND  OF  MAGNET 

quantity  of  filings  was  placed  in  a  glass  tube  and  a  strong 
current  was  sent  through  a  wire  wound  around  the  tube, 
the  tube  of  filings  became  quite  an  appreciable  magnet.  If 
a  piece  of  soft  iron,  instead  of  a  tube  of  filings,  was  placed 
inside  the  coil  of  wire  carrying  a  current,  the  iron  became 
quite  a  powerful  magnet,  but  as  soon  as  the  current  ceased 
in  the  wire  the  magnetism  disappeared  too. 

If  one  takes  an  ordinary  kitchen  poker  and  wraps  an 
insulated  wire  round  and  round  it  from  one  end  to  the 
other,  whenever  the  two  ends  of  the  wire  are  connected  to 
a  battery  the  poker  becomes  a  powerful  magnet,  and  will 
support  pieces  of  iron,  such  as  keys,  scissors,  nails,  etc. 
As  soon  as  the  current  is  stopped  in  the  wire  by  discon- 
necting it  from  the  battery,  down  tumble  all  the  objects, 
for  the  magnetism  has  vanished  from  the  poker.  Here 
we  have  a  most  useful  kind  of  magnet,  which  will  attract 
or  let  go  at  will ;  and  such  magnets  or  electro-magnets  are 
of  the  very  greatest  importance  to  us  in  telegraphs,  tele- 
phones, dynamos,  motors,  etc. 

Electro-magnets  are  made  of  soft  iron,  but  if  hard  steel 
were  substituted  inside  the  coil  of  wire,  the  steel  would  be 
much  slower  in  replying  to  the  influence  of  the  current, 
and  when  the  current  was  stopped  it  would  be  found  that 
the  magnetism  remained,  and  the  wire  could  then  be 
removed.  The  steel  magnets  thus  made  are  called  per- 
manent magnets,  to  distinguish  them  from  electro-magnets, 
which  are  merely  temporary.  The  magnetic  needle  in  the 
compass  is  of  course  a  steel  magnet,  as  also  were  the  toy 
magnets  of  our  youth. 

Iron,  like  all  other  substances,  is  built  up  of  very  small 
particles,  called  molecules,  which  are  so  exceedingly  small 

43 


WHAT  HAPPENS   IN  A  MAGNET 

that  they  are  far  beyond  the  reach  of  the  most  powerful 
microscopes.  Of  course,  we  must  magnify  these  mole- 
cules immensely  in  our  minds  when  we  think  of  them,  no 
matter  how  small  we  try  to  picture  them. 

Each  of  these  molecules  of  iron  is  itself  a  tiny  magnet, 
having  of  necessity  a  north  and  a  south  pole.  In  the  iron 
these  are  all  lying  higgledy-piggledy,  the  pull  of  one 
counteracting  the  pull  of  another,  so  that  no  trace  of 
magnetism  is  found  in  the  iron. 

It  has  already  been  shown  that  a  magnet  inside  a  coil 
of  wire  will  turn  round  and  set  itself  at  right  angles  to 
the  coil  whenever  a  current  of  electricity  is  passing  in  the 
wire.  Therefore,  each  molecule  in  the  iron  core  of  the 
electro-magnet  will  behave  in  the  same  fashion,  for  each 
molecule  being  a  tiny  magnet  will  turn  round  and  set 
itself  at  right  angles  to  the  wire,  with  its  north  pole  in 
one  direction  and  its  south  pole  in  the  opposite  direction. 
All  the  combined  north  poles  of  these  midget  magnets 
now  acting  together  produce  a  very  effective  power  of 
attraction,  as  also  do  the  united  forces  of  the  south  poles. 
Thus  at  the  one  end  of  an  electro-magnet  is  found  a 
north  pole  and  at  the  other  end  a  south  pole,  no  matter 
whether  the  magnet  be  a  straight  bar  or  bent  in  horse- 
shoe form. 

It  is  quite  reasonable  to  suppose  that  in  hard  steel 
these  tiny  molecules  are  so  firmly  bound  together  that 
when  the  current  once  gets  them  turned  round  they  can- 
not readily  swing  back  again,  in  which  case  we  have  a 
permanent  magnet.  On  the  other  hand,  in  soft  iron  the 
molecules  will  reply  much  quicker  to  the  controlling 
current,  but  will  only  remain  with  their  north  poles  all  in 

44 


AN  INTERESTING   THEORY 

one  direction  as  long  as  the  neighbouring  current  holds 
them  there ;  as  soon  as  the  current  is  withdrawn  they 
swing  back  to  their  normal  higgledy-piggledy  condition.* 

One  may  imagine  the  turning  on  of  the  current  to  be, 
in  military  parlance,  the  command  of  "Eyes  front "  to 
this  regiment  of  molecules ;  the  withdrawal  of  the  current 
to  be  the  "  Stand  at  ease  "  or  "  Stand  easy." 

If  this  generally  accepted  theory  of  magnetism  be 
correct,  then  one  can  foresee  what  will  happen  if  a  so- 
called  permanent  steel  magnet  be  raised  to  a  red  heat. 
As  its  molecules  will  be  set  in  rapid  vibratory  movement 
they  will  be  given  an  opportunity  of  freeing  themselves 
from  the  artificial  position  into  which  they  were  forced 
by  the  effect  of  the  electric  current.  This  exactly  corre- 
sponds with  what  does  take  place,  for  no  trace  of 
magnetism  is  found  in  the  "  permanent "  magnet  when  it 
has  been  thoroughly  heated.  For  the  same  reason  one 
must  be  careful  not  to  knock  these  steel  magnets  about, 
for  by  hammering  them  one  may  assist  the  molecules  back 
to  their  normal  positions. 

Strange  to  say,  when  a  piece  of  iron  rod  is  magnetised 
it  becomes  longer  and  thinner,  but  this  is  quite  in  keeping 
with  a  turning  movement  provided  the  molecule  is  of 
irregular  shape.  The  metals  nickel  and  cobalt  are  also 
magnetic  substances,  and  indeed  it  appears  as  though  all 
matter  is  more  or  less  magnetic,  but  iron  stands  out  head 
and  shoulders  above  all  other  materials  in  its  magnetic 
properties.  It  has  been  found  possible,  however,  to  pro- 

*  It  is  not  necessary  to  suppose  a  real  topsy-turvy  condition,  for  if 
the  tiny  magnets  were  forming  complete  magnetic  chains  or  rings  the 
absence  of  any  outward  effect  would  be  just  the  same. 

45 


AN  INTERESTING  THEORY 

duce  alloys  of  copper,  manganese,  and  aluminium,  which 
have  proved  much  more  magnetic  than  nickel  and  cobalt, 
though  falling  far  short  of  iron. 

It  is  quite  possible  to  magnetise  a  piece  of  steel  by  the 
earth's  influence,  if  the  metal  is  placed  in  a  definite 
position  in  relation  to  the  magnetic  poles  of  the  earth 
and  then  hammered  in  order  to  give  the  molecules  an 
opportunity  of  getting  into  position.  Steel  railings  after 
standing  for  many  years  in  one  position  have  often  been 
found  to  be  quite  appreciable  magnets,  as  also  have  steel 
rails  of  a  railway  track. 


CHAPTER  V 

HOW  MAGNETISM   IS  RELATED 
TO  ELECTRICITY 

A  magnet  without  any  iron— A  British  scientist  makes  a  simple  dis- 
covery which  leads  to  great  things — Some  absurd  mistakes  between 
magnetic  and  electrical  attraction — How  the  iron  molecule  pos- 
sesses magnetism— Some  notable  examples  of  perpetual  motion— 
What  happens  to  the  molecule  when  highly  heated— A  military 
analogy. 

WHEN  magnetism  and  electricity  were  at  first 
known  there  was  not  supposed  to  be  any  con- 
nection between  them ;   then  for  a  time  they 
were  treated  as  sister  sciences,  while  now  one  would  feel 
it  more  natural  to  have  but  one  scientific  name  to  dis- 
tinctly include  both. 

In  the  preceding  chapter  we  saw  that  an  electric  current 
flowing  in  a  wire  around  a  piece  of  iron  produced  mag- 
netism in  the  iron.  If  the  iron  is  withdrawn  altogether, 
it  will  be  found  that  the  coil  of  copper  wire  is  itself  a 
magnet,  as  long  as  the  current  flows  in  it. 

If  a  light  coil  of  fine  insulated  copper  wire  be  freely 
suspended,  and  attached  to  a  battery,  it  will  be  found 
that  the  coil,  with  the  current  passing  through  it,  behaves 
exactly  like  an  iron  magnet.  One  face  of  the  coil  will 
be  attracted  by  the  north  pole  of  a  bar-magnet,  while 
the  other  face  will  be  repelled,  showing  that  the  coil  has 

47 


A  SIMPLE  DISCOVERY 

a  north  and  a  south  pole.    When  a  piece  of  iron  is  placed 
inside  the  coil  the  effect  is  greatly  increased. 

We  see  that  an  electric  current  produces  a  magnetic 
field  *  in  its  neighbourhood.  A  piece  of  ordinary  iron, 
when  placed  in  this  field,  becomes  a  magnet.  Therefore 
if  we  possess  an  electric  current  we  may  produce  magnet- 
ism in  a  piece  of  iron. 

In  the  foregoing  statement  we  see  a  very  close  relation- 
ship between  electricity  and  magnetism,  but  this  is  not 
all.  We  shall  see  that  if  we  have  a  magnet  we  may 
obtain  an  electric  current  in  a  neighbouring  coil  of  wire. 

It  was  some  seventy  years  ago  that  our  great  British 
scientist,  Michael  Faraday,  discovered  that  when  a  coil 
of  wire  was  quickly  moved  between  the  poles  of  a  magnet, 
an  electric  current  was  set  up  in  the  wire  at  each  move- 
ment. 

We  have  all  seen  this  experiment  repeated  in  those 
small  magneto-electric  machines,  in  which  one  drives  a 
coil  of  wire  round  in  the  magnetic  field  of  a  permanent 
magnet.  Such  machines  are  sometimes  used  for  medical 
purposes,  but  perhaps  more  often  for  amusement. 

This  very  simple  little  experiment  of  Faraday's  in  time 
gave  birth  to  our  gigantic  dynamos  and  motors,  and  when 
we  think  of  all  that  these  mean  we  shall  surely  not  fail  to 
put  a  true  measure  of  value  upon  the  patient  research 
work  of  scientific  men. 

Many  people  make  a  strange  confusion  between  the 
meaning  of  magnetic  attraction  and  the  attractive  power 
of  an  electrified  body.     I  remember  a  student,  when  re- 
plying to  a  question  as  to  how  one  may  magnetise  a  piece 
*  A  magnetic  field  means  a  space  in  which  we  find  magnetic  force, 

48 


THE   IRON  MOLECULE 

of  steel,  writing  down  in  all  seriousness,  "  Rub  it  with 
a  piece  of  silk  or  flannel,"  showing  that  he  had  confused 
magnetic  attraction  with  the  electrical  attraction  exhibited 
by  an  "excited"  glass  rod,  etc.  Equally  absurd  was 
another  instance,  which  happened  at  the  close  of  a  lecture 
to  young  people.  I  had  demonstrated  electrical  attraction 
by  "charging"  a  young  girl  by  means  of  an  electrical 
machine,  and  then  showing  her  hair  attracted  to  my  hand 
when  held  over  her  head.  When  the  lecture  was  over 
I  noticed  a  young  electrical  engineer-elect  place  a  girl 
upon  the  insulated  stool,  but  not  in  connection  with  any 
source  of  electricity,  and  then  merely  holding  a  large  steel 
magnet  over  the  child's  head,  he  was  quite  surprised  to 
find  that  her  hair  did  not  rise  to  the  occasion,  he  attribut- 
ing the  failure  to  dampness  of  the  glass  legs  of  the  stool. 
These  are  extreme  cases,  but  they  illustrate  a  difficulty 
that  cannot  exist  if  one  realises  that  a  magnet  attracts 
only  iron  to  any  appreciable  extent,  whereas  an  electrified 
body  will  attract  any  substance. 

The  coil  of  wire  carrying  an  electric  current  is  not  an 
electrified  body.  One  may  picture  an  electrified  body  as 
having  a  charge  of  electricity  at  rest  in  a  strained  condi- 
tion, while  a  body  conveying  a  current  has  electricity  in 
locomotion. 

In  the  molecular  theory  of  magnetism,  briefly  explained 
in  the  preceding  chapter,  it  is  obvious  that  the  question 
as  to  what  magnetism  is  has  only  been  answered  in  part. 
This  theory  does  not  go  to  the  root  of  the  matter,  as  it 
sets  out  with  the  assumption  that  each  molecule  of  iron 
is  itself  a  magnet.  Where  does  the  molecules  magnetism 
come  from  ?  It  is  supposed  that  there  is  electricity  in 

D  49 


THE   SATURATION   POINT 

motion  around  the  atoms  of  iron,  and  that  each  miniature 
electric  current  sets  up  a  tiny  magnetic  field.  It  will  be 
understood  that  a  molecule  is  merely  a  group  of  atoms. 
The  iron  which  we  see  is  in  reality  a  great  congregation 
of  these  invisible  molecules.  Therefore  the  iron  has 
within  it  a  myriad  of  miniature  magnets.  When  these 
are  all  acting  unitedly,  the  lump  of  iron  shows  very 
appreciable  signs  of  magnetism,  but  when  these  tiny 
magnets  are  all  at  sixes  and  sevens,  there  is  no  outward 
sign  of  magnetism. 

We  may  picture  a  lump  of  iron,  in  the  latter  condition, 
being  placed  within  a  coil  of  wire  in  which  an  electric 
current  is  flowing.  All  the  tiny  magnets  wheel  round 
into  the  one  position,  and  we  say  that  the  iron  has 
become  a  magnet.  It  will  be  observed  that  the  magnetic 
force  was  existent  already  within  the  iron,  and  that  the 
influence  of  the  neighbouring  electric  current  merely  set 
these  tiny  forces  in  order. 

If  we  place  a  piece  of  gold  or  silver  within  the  electric 
coil,  we  do  not  get  any  signs  of  magnetism  in  these  metals, 
because  they  do  not  contain  the  myriads  of  magnetic 
atoms  which  we  find  always  in  iron.  However,  we  have 
seen  in  the  preceding  chapter  that  alloys  of  certain  non- 
magnetic substances  such  as  copper,  manganese,  and 
aluminium  have  shown  quite  respectable  signs  of  magnet- 
ism when  treated  in  the  same  way. 

There  is  one  point  which  is  worth  mentioning.  We 
used  to  say  that  iron  could  be  magnetised  to  a  certain 
extent  and  no  further.  This  was  called  the  saturation 
point.  The  mental  picture  we  formed  in  those  days  was 
that  of  soaking  magnetism  into  the  iron  till  it  could  hold 

50 


ELECTRICAL  PHENOMENA 

no  more.  Now  we  have  a  much  more  reasonable  picture. 
As  the  magnetic  force  resides  already  within  the  iron, 
it  is  quite  clear  that  we  can  get  a  certain  degree  of  mag- 
netism and  that  we  can  get  no  more  from  the  iron,  no 
matter  how  powerful  an  electric  current  we  use.  It  will 
be  clear  also  why  a  piece  of  soft  iron,  when  placed  within 
a  coil  carrying  an  electric  current,  increases  the  magnetic 
field.  The  iron  adds  to  the  magnetic  field  the  magnetism 
which  is  already  locked  up  within  the  iron. 

We  shall  be  able  to  form  a  much  clearer  picture  of  the 
nature  of  magnetism  when  we  come  to  consider  the 
present  ideas  concerning  electrical  phenomena.  In  the 
meantime  we  are  quite  able  to  step  out  into  the  world 
of  practical  electricity.  There  we  shall  find  that  all  the 
great  uses  to  which  electricity  has  been  put  are  merely 
applications  of  the  simple  phenomena  set  forth  in  the 
preceding  chapters. 


CHAPTER  VI 

HOW  WE   CAME  TO  HAVE  THE 
TELEGRAPH 

A  Highlander's  amusing  explanation — Man's  earliest  method  of 
signalling  —  The  first  really  practical  electric  telegraph— An 
American  rival  which  came  to  stay — An  instrument  to  record  the 
telegraph  signals  received— Why  a  complete  circuit  is  required  for 
an  electric  current — How  one  wire  can  now  be  used. 

THERE  is  an  amusing  story  in  connection  with  the 
early  days  of  the  telegraph  which,  whether  real  or 
fictitious,  will  serve  to  illustrate  a  point  of  much 
importance.  One  Scottish  Highlander  is  said  to  have 
asked  another  how  the  telegraph  worked,  whereupon  the 
second  one  replied  that  he  didn't  understand  it  but  he 
thought  he  could  explain  it,  from  which  remark  one 
would  infer  that  he  had  some  Irish  blood  in  him.  Finding 
a  convenient  illustration  in  his  faithful  collie,  he  asked  his 
friend  to  imagine  the  dog  stretching  itself  and  yet 
stretching  itself  until  its  head  reached  Glasgow  while  its 
hindquarters  remained  in  Oban.  If  he  were  then  to 
tramp  upon  the  dog's  tail  it  would  bark  at  the  Glasgow 
end,  but  he  was  careful  to  add  that  as  it  was  not  very 
convenient  to  stretch  a  dog  so  great  a  distance,  the 
telegraph  folk  put  up  a  piece  of  wire  which  seemed  to  act 
just  as  well. 

5* 


EARLIEST  METHOD  OF  SIGNALLING 

While  the  Highlander's  explanation  may  not  make  the 
details  of  electric  telegraphs  very  clear  to  us,  yet  there  is 
one  point  in  the  story  which  cannot  be  too  well  emphasised, 
and  that  is,  that  there  is  a  medium  of  communication 
between  the  two  places,  and  this  there  always  must  be, 
even  in  the  case  of  wireless  telegraphy. 

Early  in  the  world's  history  man  found  it  necessary  to 
be  able  to  signal  to  a  distance,  and  so  he  adopted  the 
method  of  lighting  beacon  fires  upon  the  hill-tops,  and 
these  signals  could  be  passed  on  from  one  point  to  another. 
Of  course  these  men  in  ancient  times  had  arranged  with 
their  distant  friends  that  when   a  fire  was   seen   upon 
the  hill-top  it  would  mean  a  certain  thing.     When  we 
moderns   wish   to   communicate   with   our  friends   at  a 
distance  we  have  to  use  prearranged  signals  in  the  same 
way.     We  find  it  convenient  still  to  use  visual  signals  for 
military   and   naval   purposes,  such   as    by  the   waving 
of  flags.     All  such  systems  are  limited  necessarily  to  very 
short  distances. 

When  one  sees  a  magnet  turning  first  to  one  side  and 
then  to  the  other,  according  to  the  direction  in  which  an 
electric  current  is  sent  through  a  coil,  it  is  a  very  natural 
step  from  that  to  the  first  practical  electric  telegraph 
instrument.  It  is  apparent  that  if  one  person  had  the 
coil  and  magnet  in  his  house  and  another  had  the  battery 
at  his  home,  while  the  wires  still  connected  the  battery  to 
the  coil  the  second  person  could  cause  the  magnet  beside 
the  first  to  move  to  one  side  or  the  other  at  will,  and  by 
an  agreed  code  intelligible  signals  could  be  transmitted. 

The  needle  telegraph  is  just  this  coil  and  magnet  and 
nothing  more,  except  that  it  is  put  into  a  more  convenient 

S3 


FIRST   ELECTRIC  TELEGRAPH 

form.  The  magnet  is  fixed  to  a  spindle  passed  through 
its  centre,  and  is  then  mounted  in  a  vertical  position  at 
the  back  of  an  upright  board;  the  coil  is  then  placed 
around  it,  leaving  the  needle  free  to  fall  to  right  and  left. 
Then,  so  that  the  movements  of  the  needle  may  be  readily 
seen,  an  indicator  or  dummy  needle  is  fixed  on  the  other 
end  of  the  spindle,  which  comes  through  to  the  front  of 
the  board.  This  indicator  or  needle  moves,  of  course, 
along  with  the  magnet  at  the  back,  and  so  the  signals  are 
clearly  read.  An  arrangement  for  reversing  the  current  at 
will,  in  order  to  move  the  needle  to  one  side  or  the  other, 
is  added,  and  this  may  be  operated  by  moving  a  handle 
from  left  to  right,  or  by  depressing  one  or  other  of  two 
small  levers  or  "  keys."" 

It  might  be  a  matter  of  agreement  to  signal  one  move- 
ment of  the  needle  for  A,  two  for  B,  and  so  on ;  but  the 
operator  would  very  soon  weary  of  this  plan  if  he  had 
many  letters  far  on  in  the  alphabet  to  count  out.  Imagine 
our  written  language  being  constructed  thus : — I  for  A, 
II  for  B,  III  for  C,  and  so  on.  It  is  much  more  con- 
venient to  let  two  strokes  leaning  against  each  other  with 
a  third  stroke  crossing  them  stand  for  A,  three  strokes 
placed  thus  for  N,  thus  for  Z ;  and  so  in  telegraphy  it  is 
agreed  that  if  the -needle  is  moved  once  to  the  left  and 
then  once  to  the  right  (\/)  this  will  signify  A.  It  is 
quite  remarkable  that  in  order  to  construct  the  whole 
twenty-six  letters  of  the  alphabet  by  combinations  of 
these  two  movements  we  never  require  to  move  the  needle 
more  than  four  times  for  any  letter.  It  evidently  did  not 
occur  to  the  experimenters  at  the  outset  that  this  could 
be  done,  as  they  made  the  early  instruments  with  five 

54 


FIRST  ELECTRIC  TELEGRAPH 

needles  in  order  to  get  a  greater  variety  of  signal,  their 
idea  being  to  make  the  needles  point  out  the  letters  on  a 
dial. 

SIGNALS  FOR  NEEDLE  TELEGRAPH 


V     * 

\/ 

«/ 

x/// 

* 

XXX                   > 

s 

Axx 

/f 

A/ 

T 

/ 

AA 

L 

xAx 

»^  /    w*/rr£#  rttfft/ 

o 

Ax 

M 

// 

V 

XXX  / 

£ 

X 

A/ 

A 

W 

x// 

f 

XX  A 

O 

/// 

X 

/xx/ 

c 

/A 

/> 

x/A 

Y 

A// 

// 

xx\\ 

4 

/A/ 

Z 

//xx 

/ 

XX 

ft 

x/x 

FIG.  3 

Referring  to  the  accompanying  alphabet,  it  will  be  seen 
that  the  letters  most  often  in  use  get  the  advantage  of 
the  simplest  signals.  Once  to  the  left  stands  for  E  ;  once 
to  the  right  for  T ;  and  so  on.  It  is  usual  to  print  the 
left-hand  strokes  shorter  than  the  right-hand  ones,  as 
shown  ;  but  this  is  merely  for  convenience  of  space. 

Our  own  alphabet  is  of  very  simple  construction  ;  give  a 
boy  four  straight  strips  of  cardboard,  each  representing  a 
stroke,  and  he  can  with  these  construct  more  than  half 
the  alphabet,  while  a  few  semicircular  pieces  added  will 
enable  him  to  complete  the  whole  twenty-six  letters. 

While  Cooke  and  Wheatstone  were  the  first  (1837)  to 
set  up  a  needle  telegraph  in  this  country,  we  cannot 
claim  the  invention  for  them,  as  Professor  Ampere,  of 
Paris,  had  suggested  fifteen  years  earlier  that  a  magnet 
and  coil  placed  at  any  distant  point  of  a  circuit  would 

55 


AN  AMERICAN  RIVAL 

serve  for  the  transmission  of  signals ;  and  other  experi- 
menters in  Germany  had  actually  carried  this  out  with 
success. 

Simple  as  this  method  is,  there  was  a  yet  simpler  plan 
adopted  in  New  York  about  the  same  time  as  the  former 
was  set  up  in  London.  Knowing  that  an  electro-magnet 
would  attract  and  let  go  at  will,  a  piece  of  iron  was  sus- 
pended by  a  spring  so  that  it  stood  close  over  the  poles 
of  the  electro-magnet.  Whenever  a  current  was  sent 
along  the  wire  to  the  electro-magnet  it  would  attract  the 
iron  and  hold  on  to  it  as  long  as  the  current  was  left  on, 
but  as  soon  as  the  circuit  was  broken  the  magnet  lost  its 
power,  so  that  the  iron  was  pulled  away  by  the  suspend- 
ing spring.  The  movable  piece  of  iron  was  mounted  on 
one  end  of  a  small  lever,  the  other  end  of  which  worked 
between  two  stops,  so  that  each  time  the  iron  armature 
was  attracted  downwards  it  caused  the  other  end  of  the 
lever  to  "  click  "  against  the  upper  stop,  and  by  this  means 
signals  or  intelligible  "raps"  were  made.  If  the  lever 
clicked  against  the  upper  stop  and  then  immediately  fell 
back  on  to  the  lower  stop,  that  indicated  the  letter  E, 
but  if  after  striking  the  upper  stop  it  remained  a  little 
before  falling  back  on  the  other  stop,  then  the  letter  T 
was  signalled.  If  the  lever  gave  three  quick  successive 
clicks  the  letter  S  was  to  be  understood,  and  so  on. 

This  method  saves  the  trouble  of  reversing  the  current 
which  was  necessary  in  the  needle  telegraph ;  all  that  is 
required  in  this  American  invention  is  to  make  and  break 
the  current's  path.  While  this  system  of  telegraphy  had 
been  suggested  by  a  great  American  scientist,  Henry,  as 
early  as  1831,  it  was  not  till  1837  that  another  American, 

56 


TELEGRAPH   SIGNALS 

Morse,  brought  the  instrument  into  practical  use.  Work- 
ing by  clicks  it  is  called  the  "  morse-sounder."  Morse 
also  arranged  that  the  instrument  should  record  the 
signals  received  by  marking  them  on  a  strip  of  paper, 
and  this  has  b^en  termed  a  "  morse-inker. "  If  one  end 
of  the  armature  lever  is  fitted  with  a  small  wheel,  which 

SIGNALS   FOR   MORSE  TELEGRAPH 


A  -  — 

r/  .  «.  —  ». 

5  --- 

a  —  --- 

/r  

T  — 

c  —  -  —  - 

^.  —  .. 

^  .-  — 

z?  —  -  « 

/I/  —  — 

^  

£-  - 

>v  —  - 

W  

/•  .  .  —  - 

^  

X  

#  

/>  . 

Y  

>y  

^  

Z  

y  .. 

>?  

FIG.  4  _ 

when  at  rest  dips  into  a  small  ink-well,  and  if,  instead  of 
coming  in  contact  with  a  stop  when  raised,  the  wheel 
touches  a  paper  ribbon,  which  is  kept  in  motion  by 
clockwork,  then  a  mark  will  be  made  along  the  centre  of 
the  paper  as  long  as  the  wheel  is  held  up  by  the  magnet 
at  the  other  end  of  the  lever.  It  is  therefore  an  easy 
matter  to  make  long  or  short  strokes  at  will  by  keeping 
the  current  on  for  different  lengths  of  time.  That  is  all 
this  instrument  can  do,  make  short  and  long  strokes, 
usually  called  dots  and  dashes,  and  the  alphabet  is  made 

57 


COMPLETE  CIRCUIT  REQUIRED 

up  by  different  combinations  of  these.  The  letters  E  and 
T  being  used  oftener  than  any  other  letters  get  the 
advantage  of  a  single  short  stroke  for  E  and  a  single 
long  stroke  for  T,  as  will  be  seen  from  the  accompanying 
alphabet.  It  will  be  noticed  on  comparing  the  Morse 
and  the  needle  alphabets  that  they  are  really  identical ; 
a  short  stroke  or  "dot"  being  equivalent  to  the  needle 
falling  to  the  left,  and  a  long  stroke  or  "dash""  to  a 
needle  movement  to  the  right  hand.  With  constant 
practice  this  alphabet  becomes  as  natural  to  the  operator 
as  our  everyday  ABC,  and  I  have  heard  of  two 
telegraph  operators  carrying  on  a  silent  conversation 
with  each  other  by  a  slight  movement  of  the  left  and 
right  eyes.  Underneath  the  Morse  alphabet  (see  p.  57) 
will  be  found  a  short  sentence  of  two  words,  which  may 
easily  be  deciphered. 

A  bald  statement  that  an  electric  current  must  always 
have  a  complete  circuit  does  not  appeal  very  forcibly  to 
many  minds.  I  have  seen  people  quite  at  sea  in  trying 
to  arrange  a  simple  electric  circuit,  such  as  connecting  up 
a  bell,  push,  and  battery.  There  need  not  be  the  very 
slightest  confusion  if  one  clearly  keeps  in  mind  what  is 
taking  place  when  a  battery  sends  a  current  of  electricity 
along  a  wire.  All  that  the  battery  does  is  to  cause  an 
electric  current  to  pass  from  its  carbon  plate  to  its  com- 
panion zinc.  We  fix  a  short  wire  across  from  the  one 
plate  to  the  other,  and  an  electric  current  passes  along 
the  wire  on  its  way  from  the  carbon  to  the  zinc.  We 
may  make  the  wire  a  mile  long,  or  as  long  as  we  please, 
and  the  current  must  pass  by  this  route  on  its  way  from 
the  one  plate  to  the  other.  If  we  carry  the  wire  to 

5* 


COMPLETE  CIRCUIT  REQUIRED 

Land's  End  and  back,  then  before  the  current  can  get 
from  the  carbon  to  its  close  neighbour  the  zinc  plate, 
it  is  forced  to  travel  via  Land's  End.  If  the  wire  circuit 
is  broken  at  any  place  the  current  immediately  ceases,  as 
it  has  no  path  left  from  the  carbon  to  the  zinc;  if  the 
wires  are  touched  together  again,  the  current  once  more 
passes.  The  ordinary  electric  bell  push  is  merely  a  means 
of  making  and  breaking  the  circuit. 

If  the  wire  of  our  imaginary  Land's  End  circuit  be 
cut  at  that  distant  place  and  the  two  free  ends  be  joined 
to  the  two  ends  of  the  coil  in  a  needle-telegraph  instru- 
ment, then  the  current  in  going  from  the  carbon  to  the 
zinc  in  the  battery  has  to  pass  through  this  distant  tele- 
graph instrument,  as  its  coil  has  become  part  of  the 
circuit.  The  necessity  for  a  complete  circuit  is  therefore 
quite  apparent  (see  Fig.  5). 

While  fitting  up  a  telegraph  installation  on  a  railway 
in  1838,  Steinheil,  of  Munich,  noticed  that  his  return  wire 
was  broken,  and  the  two  ends  were  put  into  the  earth ; 
the  current  passed  just  as  though  the  wires  were  joined 
together.  It  was  soon  found  that  it  did  not  matter  how 
far  distant  these  earth  connections  were,  so  that  if  a  tele- 
graph is  to  be  fitted  up  between  London  and  John 
O'Groat's  a  wire  is  led  from  the  carbon  in  the  battery 
at  London  all  the  way  to  that  northern  limit  of  the 
Scottish  mainland  and  there  connected  to  one  end  of  the 
telegraph  coil.  Instead  of  now  bringing  a  return  wire 
from  the  other  end  of  the  coil  right  back  to  the  zinc  of 
the  London  battery,  a  short  wire  is  simply  connected 
to  the  earth  at  the  Scottish  end,  while  at  the  London 
end  another  short  wire  is  led  from  the  earth  to  the  zinc  in 

59 


HOW   ONE   WIRE   CAN   BE   USED 

the  battery  there.  At  the  London  end  it  would  be  quite 
sufficient  to  fasten  the  short  wire  from  the  zinc  to  any 
water-pipe  in  the  building  and  thereby  get  into  contact 
with  the  earth,  but  not  finding  a  similar  convenience  at 


FIG.  5 

SHOWING   A   CELL  CONNECTED   TO   A  TELEGRAPH   INSTRUMENT 

the  northern  house  it  would  be  found  necessary  to  attach 
the  wire  to  a  copper  plate  and  then  bury  it  in  the  moist 
subsoil.  In  Fig.  6  an  earth  circuit  is  shown  in  which 
both  ends  are  attached  to  buried  plates. 

It  was  originally  supposed  that  the  current  of  electricity 
passed  through  the  earth  from  the  one  plate  to  the  other, 
but  it  seemed  afterwards  more  reasonable  to  picture  the 
current  as  being  dissipated  in  the  earth  at  the  one  end 
and  fed  on  at  the  other  end.  An  analogy  portrays  the 
earth  as  a  great  ocean,  the  wire  like  a  pipe  with  its  two 
free  ends  dipping  into  the  ocean  at  far  separated  points, 
and  the  battery  as  a  pump  propelling  the  current  along. 
Whatever  mental  picture  we  form,  we  must  remember 
that  the  electric  current  is  not  a  material  fluid. 

There  is  no  difficulty  in  sending  a  current  over  this 

60 


HOW   ONE   WIRE   CAN  BE  USED 

single  wire  with  its  earth  circuit,  but  one  is  not  surprised 
to  learn  that  when  any  great  natural  disturbance  takes 
place  in  this  ether-ocean  into  which  the  wires  are  dipping, 


FIG.  6 
HOW  A  TELEGRAPH  IS  WORKED  WITH  A  SINGLE  WIRE 

the  current  in  these  earth-connected  wires  is  very  appre- 
ciably affected,  our  whole  telegraph  system  being  some- 
times quite  upset  during  a  magnetic  storm. 


CHAPTER  VII 
HOW   WE   NOW   SEND   TELEGRAMS 

Beginning  of  public  telegraphs — A  telegram  outruns  a  murderer — 
Impetus  to  telegraphs— Government  takes  control— A  country 
postmaster  baffled— Speech  wired  in  half  the  time  of  delivery — 
How  high  speeds  are  attained— How  a  failing  current  hands  the 
signals  to  a  vigorous  current— Several  messages  pass  simultane- 
ously on  one  wire — Some  clever  inventions— Ordinary  writing  by 
telegraph — Typewriting  telegraphs — Enormous  telegraph  business 
— Telegraph  versus  telephone. 

WHEN  His  Majesty  the  King  was  born,  in  1841, 
the   good   news  was  not   heralded  across  the 
country  by  the  telegraph,  for  the  very  good 
reason  that  not  a  single  telegraph  line  connected  any  two 
towns  together,  the  invention  having  only  been  applied 
to  a  few  short  private  lines  along  the  railways. 

In  the  United  States  things  were  in  very  much  the 
same  position,  the  first  commercial  line  of  telegraph  not 
being  opened  until  1844,  when  Washington  was  con- 
nected with  Baltimore. 

One  would  have  expected  this  great  invention  to  be 
received  by  the  people  with  open  arms,  but  in  this 
country  the  inventors  could  not  get  anyone  to  take  an 
interest  in  the  matter  excepting  railway  companies,  which 
were  at  that  time  few  in  number,  so  that  the  first  five 
years'  working  entailed  a  serious  loss  to  the  inventors. 
How  long  things  might  have  continued  in  this  way  but 

62 


PUBLIC  TELEGRAPHS 

for  a  chance  incident  it  is  difficult  to  say,  and  indeed  one 
would  not  have  been  surprised  to  learn  of  the  inventors 
determining  to  abandon  the  scheme  and  lose  no  more 
money.  It  so  happened  that  a  Quaker,  having  com- 
mitted a  murder  near  Slough,  fled  to  the  Great  Western 
Railway  and  took  train  to  London,  but  the  news  of  the 
dreadful  deed  reached  the  station  at  Slough  soon  after  his 
train  had  left.  One  can  imagine  the  disappointed  pur- 
suers possibly  thinking  "  a  miss  is  as  good  as  a  mile,"  for 
no  living  being  could  hope  to  overtake  the  train ;  but 
someone  suggested  getting  the  railway  officials  to  send 
word  over  their  telegraph  line  to  London.  A  full  de- 
scription of  the  Quaker  and  particulars  of  what  had 
happened  were  spelt  out  by  the  needle  telegraph,  so  that 
the  murderer,  while  no  doubt  congratulating  himself 
that  he  had  outrun  any  chance  of  arrest,  was  startled  to 
find  that  news  of  his  crime  had  reached  London  before 
him,  as  he  was  "shadowed"  on  his  arrival  and  quietly 
arrested. 

One  can  imagine  the  news  of  this  wonderful  capture 
spreading  through  London  and  from  town  to  town  till 
the  country  began  to  praise  the  telegraph  as  a  right 
useful  messenger.  Investors,  who  had  previously  looked 
upon  the  electric  telegraph  as  too  risky  a  business,  would 
now  be  most  willing  to  give  financial  support.  The 
Electric  Telegraph  Company  was  soon  formed,  and 
within  three  years  about  1,500  miles  of  wire  were  erected, 
and  before  our  King  was  eight  years  of  age,  London,  Bir- 
mingham, and  Manchester  were  in  direct  communication 
by  telegraph.  It  was  not  long  before  other  private  com- 
panies were  formed. 

63 


GOVERNMENT   CONTROL 

A  telegram  in  those  days  meant  important  news ;  even 
the  wealthy  would  not  have  thought  of  wiring  such 
messages  as  "  Will  come  to  see  you  to-morrow  afternoon  ; 
wire  if  convenient,"  for  such  a  telegram  would  have  cost 
four  or  five  shillings,  even  for  a  short  distance,  while  the 
minimum  charge  between  London  and  Edinburgh  or 
Glasgow  was  twelve  shillings. 

After  about  ten  years1  working,  one  of  the  telegraph 
companies  tried  to  adopt  a  universal  rate  of  one  shilling, 
but  the  opposition  of  the  other  companies  was  too  strong. 
Five  years  later  all  the  companies  agreed  to  a  big  reduc- 
tion in  rates,  with  the  idea  of  increasing  business,  and  this 
proved  a  great  success. 

It  is  very  well  that  the  Government  took  over  the  tele- 
graph business  in  1870,  for  it  was  only  natural  that  the 
private  companies  would  not  extend  their  telegraph  lines 
into  districts  where  they  could  not  hope  for  a  profitable 
return.  The  Government  could  afford  to  take  a  less  mer- 
cenary view,  and  small  towns  and  villages  soon  had  their 
post  offices  connected  by  telegraph  with  the  nearest  large 
town,  till  now  a  perfect  network  of  wires  extends  across 
the  country  in  all  directions. 

It  is  impossible  to  over-estimate  the  value  of  the  electric 
telegraph  to  the  world,  and  yet  it  would  not  be  surpris- 
ing to  find  some  people  willing  to  denounce  this  invention 
as  the  destroyer  of  the  once  peacefully-quiet  life  of  the 
"good  old  times."  There  is  no  doubt  that  the  electric 
telegraph  and  the  steam-engine  are  the  two  chief  factors 
in  producing  the  hurry-scurry  of  the  present  day;  but 
surely  it  is  quite  unnecessary  to  set  forth  the  very  great 
advantages  which  these  inventions  have  brought  into  our 

64 


COUNTRY  POSTMASTER  BAFFLED 

everyday  life  by  putting  us  in  touch  with  all  the  ends  of 
the  earth. 

The  speed  with  which  intelligence  could  be  conveyed  to 
a  distance  by  the  electric  telegraph,  as  compared  with  all 
previous  methods,  was  so  very  great  that  the  actual  time 
required  in  manipulating  the  instrument  was  at  first 
counted  of  small  moment;  but  with  the  consequent  hasten- 
ing of  business  methods  and  the  extended  use  of  the  tele- 
graph system,  a  great  deal  of  attention  was  soon  given  to 
means  of  increasing  the  speed  at  which  messages  could  be 
despatched. 

In  country  districts  there  may  still  be  found  some  of 
the  ABC  dials,  by  which  a  word  is  slowly  spelt  out  by 
causing  an  indicator  to  move  round  a  dial  and  point  out 
the  letters  of  the  alphabet  separately.  I  remember  many 
years  ago  going  into  a  little  country  post  office  to 
despatch  a  telegram,  and  being  informed  by  the  elderly 
"postmaster""  that  he  couldn't  get  his  machine  to  work. 
He  explained  that  it  had  just  been  fitted  up,  and  that  he 
found  they  had  given  him  no  bottles  to  work  it  with,  such 
as  he  had  seen  at  a  neighbouring  village.  I  suggested 
that  possibly  his  "machine"  didn't  require  any  bottles, 
which  proved  to  be  the  case,  as  he  had  one  of  those  ABC 
dials  in  which  no  battery  is  required,  the  current  being 
obtained  by  driving  a  little  magneto  machine  in  exactly 
the  same  fashion  as  one  rings  up  on  a  telephone.  Of 
course,  the  advantage  of  these  instruments  for  country 
districts  was  that  the  operator  required  to  learn  no 
special  code  or  alphabet,  but  these  would  only  be  tolerated 
now  where  speed  is  of  little  consequence. 

Even  the  needle  telegraph,  which  is  purely  an  English 
«  65 


WIRING  A  SPEECH 

instrument,  is  much  too  slow  and  is  only  used  now  for 
small  districts  and  in  signal-cabins  on  the  railway. 

The  Morse  "  sounder,""  described  in  the  preceding  chap- 
ter, is  almost  universally  used  both  in  this  country  and  in 
the  United  States  for  ordinary  business.  As  it  is  neces- 
sary for  the  operator  to  spell  out  each  word,  and  space 
the  dots  and  dashes  correctly,  it  will  be  apparent  that 
even  in  the  hands  of  a  skilled  expert  the  time  taken  in 
sending  a  message  must  be  very  much  longer  than  the 
time  required  to  speak  the  words.  One  might  easily 
speak  180  words  in  a  minute,  but  an  operator  could  not 
signal  more  than  thirty-five  words  comfortably  in  the 
same  time,  so  that  a  two  hours'  speech  delivered  in 
Parliament,  when  telegraphed,  would  occupy  a  line  from 
London  to  another  important  centre  for  a  whole  night, 
which  would  be  a  serious  matter  for  the  economical  work- 
ing of  the  Post  Office.  Fortunately  this  is  not  necessary, 
and  although  it  may  seem  incredible,  it  is  a  fact  that  a 
two  hours'1  speech  may  be  passed  over  a  single  line  in  less 
than  half  the  time  taken  to  speak  it. 

While  the  speech  is  in  progress  the  reporters  may  hand 
their  "  copy  "  to  operators,  who  prepare  a  paper-ribbon  in 
a  punching  machine,  making  holes  to  represent  the  Morse 
signals.  With  a  full  staff  of  reporters  and  operators,  the 
whole  copy  of  the  speech  may  be  thus  ready  on  the 
punched  ribbon  almost  as  soon  as  the  delivery  of  the 
speech  is  finished,  and  it  is  only  necessary  then  to  run 
this  paper  by  clockwork  through  a  special  transmitter, 
thus  causing  the  makes  and  breaks  of  contact,  by  means 
of  the  perforated  holes,  at  a  speed  far  greater  than  can 
possibly  be  done  by  the  quickest  expert's  hand.  The 

66 


HOW  HIGH  SPEEDS  ARE  ATTAINED 

Wheatstone  automatic  sender,  which  is  in  general  use,  can 
easily  transmit  at  a  speed  of  from  250  to  400  words  per 
minute,  the  former  figure  being  counted  a  fair  working 
speed  over  a  distance. 

It  is  in  connection  with  the  automatic  transmitter  that 
the  "  morse-inker "  is  chiefly  used  to  receive  the  signals, 
but  the  latter  may,  of  course,  be  worked  by  an  ordinary 
hand  key  as  well.  If  an  automatic  transmitter  were 
merely  sending  signals  to  a  "  morse-sounder,"  it  would  be 
quite  impossible  to  read  the  clicks  by  ear.  If  they  were 
coming  in  at  a  speed  of  about  300  words  per  minute,  then 
there  would  be  as  many  as  4,500  clicks  made  against  the 
upper  stop  in  one  minute,  which  is  equivalent  to  seventy 
signals  in  each  second  of  time.  Therefore,  without  the 
morse-inker  the  automatic  transmitter  would  be  of  no 
service.  The  most  important  use  of  the  automatic  trans- 
mitters is  for  press  news,  but  they  are  also  used  for 
ordinary  messages  on  busy  lines. 

At  the  larger  telegraph  offices  all  the  instruments  are 
supplied  with  current  from  a  storage  battery,  the  number 
of  cells  for  any  one  line  depending  upon  its  resist- 
ance. The  longer  the  wire  the  greater  the  resistance, 
and  therefore  the  more  pressure  required  to  send  the 
current  through.  In  order  to  decrease  the  resistance  on 
long  wires,  they  are  made  of  better  conducting  pro- 
perties. 

When  an  electric  current  has  travelled  a  long  distance 
its  strength  is  considerably  reduced  owing  to  the  resist- 
ance of  the  wire,  so  that  an  electric  impulse,  on  reaching 
a  far-distant  town,  may  not  have  sufficient  energy  left  to 
cause  the  electro-magnet  to  attract  the  comparatively 

67 


HOW  HIGH  SPEEDS  ARE  ATTAINED 

heavy  armature  required  to  make  a  distinct  sound  or  to 
cause  a  recording  instrument  to  impress  the  signals 
clearly  on  paper.  This  apparent  difficulty  is  very  easily 
overcome,  for  as  long  as  there  is  a  very  small  current  this 
will  be  sufficient  to  cause  a  small  electro-magnet  to  attract 
a  very  light  lever,  and  the  movement  of  this  lever  can 
switch  on  a  local  battery  to  the  telegraph  instrument. 
This  small  electro-magnet  and  lever  arrangement  is  called 
a  "relay,"  or  repeater,  and  when  the  operator  depresses 
his  key,  or  when  he  makes  a  series  of  up-and-down 
movements,  the  electro-magnet  of  the  distant  relay  causes 
its  lever  to  make  a  similar  number  of  up-and-down 
movements,  so  that  this  lever  exactly  imitates  the  sending 
key  and  operates  the  telegraph  instrument  to  which  it  is 
attached. 

On  going  into  the  telegraph  room  of  a  large  post 
office  the  stranger  merely  hears  a  meaningless  rattle  of 
clicks,  but  to  the  experienced  telegraphist  it  is  just  as 
though  he  were  in  a  crowded  room  and  heard  a  number 
of  conversations  being  carried  on  by  different  parties. 
The  operators  sit  in  rows  at  narrow  tables  or  benches,  to 
which  their  telegraph  instruments  are  fixed.  The  wires 
pass  along  these  tables,  one  wire  leading  from  the  battery 
room  to  the  operator's  contact  key,  and  the  other  wire 
back  along  the  table  to  a  board  whereon  are  fastened  all 
the  ends  of  the  outside  telegraph  lines. 

One  does  not  find  a  great  network  of  wires  over  a  large 
telegraph  office,  because  the  wires  are  led  through  the 
city  underground,  and  then  they  branch  off  in  all  direc- 
tions, carried  on  the  familiar  telegraph  poles.  These 
overhead  wires  have  often  been  a  great  source  of  trouble 

68 


TWO  MESSAGES   ON  ONE  LINE 

during  a  severe  storm  of  wind  or  snow,  their  downfall 
causing  serious  dislocation  of  commercial  business,  so  that 
the  Post  Office  has  been  forced  to  make  some  of  the 
connections  between  the  more  important  cities  by  insulated 
wires  buried  in  pipes  in  the  earth. 

Even  with  overhead  connections  each  wire  means  a 
considerable  expense,  and  so  telegraphists  found  means 
of  sending  more  than  one  message  at  a  time  over  a  wire. 
It  seems  to  the  stranger  quite  ridiculous  to  attach  several 
telegraph  instruments  to  each  end  of  a  single  wire ;  one 
would  expect  an  utter  confusion  of  signals,  but  it  is  not 
so.  Every  line  of  importance  in  this  country  is  "du- 
plexed" to  carry  two  messages  at  one  time,  there  being, 
of  course,  two  operators  at  each  end.  One  of  these 
operators  sends  messages,  while  his  local  partner  is  re- 
ceiving messages  from  the  distance,  and  yet  there  is  no 
confusion, 

It  would  be  difficult  to  give  a  clear  statement  of  how 
this  is  done  without  going  into  technical  details,  so  I 
shall  merely  remark  in  passing  that  one  may  picture  the 
receiving  instrument  as  being  electrically  shielded  from 
the  outgoing  current  leaving  the  same  station,  and  only 
affected  by  the  incoming  current,  so  that  a  transmitting 
operator  at  each  end  is  sending  messages  out  to  a  receiving 
operator  at  the  opposite  end  of  the  wire.  At  large 
centres  eight  operators  use  one  wire  at  the  same  time, 
there  being  four  operators  at  each  end.  Two  operators 
are  sending  messages  out,  and  the  other  two  are  receiving 
messages,  and  each  receiver  picks  up  its  own  message  in 
this  manner.  A  current  is  kept  constantly  flowing  on  the 
wire,  neither  receiver  is  affected  by  this  current,  but  a 

69 


SOME   CLEVER  INVENTIONS 

change  in  the  strength  of  the  current  operates  the  one 
telegraph,  while  a  change  in  direction  of  the  current 
moves  the  second  receiver. 

Inventions  have  been  made  whereby  a  larger  number 
of  messages  may  be  sent  over  a  single  wire  simultaneously, 
but  these  are  not  in  everyday  use.  In  one  system  it  is 
arranged  to  give  each  operator  the  use  of  the  wire  in 
turn  ;  his  turn  recurring  as  quickly  as  he  can  possibly 
make  use  of  it.  This  system  requires  a  rapidly  revolving 
connection  at  each  end  of  the  wire,  both  mechanisms  keep- 
ing perfect  time,  and  the  mechanical  difficulties  of  keep- 
ing these  two  motors  in  absolute  harmony  with  each 
other  has  proved  too  much  for  ordinary  practice. 

Another  inventor  sends  as  many  as  a  dozen  messages  at 
one  time  over  a  single  wire,  using  telephone  receivers, 
which  each  hum  a  different  sound,  each  telephone  reply- 
ing to  its  own  signals  only.  The  sounds,  of  course, 
represent  the  clicks  of  the  Morse  alphabet. 

Among  other  recent  inventions  is  one  in  which  a  per- 
forated tape  is  prepared  to  transmit  currents  to  a  distant 
receiver  which  contains  a  tiny  mirror,  throwing  a  spot  of 
light  on  to  a  photographic  paper.  The  movements  of 
the  mirror  are  so  controlled  by  the  current  that  the 
pencil  of  light  traces  out  the  different  letters  of  the 
alphabet  upon  the  paper.  It  reminds  one  of  a  boy  re- 
flecting the  sun's  rays  against  a  wall  by  means  of  a  small 
mirror.  He  can  make  the  spot  of  light  dance  about  at 
will,  and,  if  the  irresponsive  wall  would  only  retain  the 
impression  of  the  spot  of  light,  the  boy  could  write  upon 
the  wall  with  his  pencil  of  light. 

In  the  telegraph  instrument  one  particular  set  of  per- 

70 


TYPEWRITING  TELEGRAPHS 

forations  passing  through  the  transmitter  causes  the  tiny 
mirror  in  the  receiver,  at  the  distant  end,  to  move  so  that 
the  letter  A  is  traced  upon  the  photographic  paper ; 
another  set  of  perforations  produces  B ;  and  so  on.  The 
photographic  paper,  after  receiving  these  impressions,  is 
chemically  developed,  and  fixed  by  the  receiving  instru- 
ment. This  instrument  has  the  advantage  of  a  very  high 
speed  in  working,  as  many  as  40,000  words  having  been 
telegraphed  over  a  considerable  distance  in  one  hour, 
which  means  that  the  whole  of  the  text  of  this  book 
could  be  telegraphed  in  less  time  than  one  could  read 
a  quarter  of  its  contents. 

Another  advantage  is  that  the  receiving  instrument 
delivers  the  message  to  the  operator  in  ordinary  writing. 
For  the  reception  of  press  news,  this  advantage  is  rather 
lost,  as  it  is  necessary  for  the  Post  Office  in  any  case  to 
write  out  a  number  of  copies  by  means  of  a  manifold 
book,  sending  one  copy  to  each  of  the  local  newspaper 
offices.  An  expert  will  read  the  regular  Morse  signals 
about  as  easily  as  the  ordinary  A  B  C,  so  that  the  longhand 
written  message  is  of  no  great  advantage  to  him. 

There  seems  to  be  a  large  field  open  for  typewriting 
telegraphs.  These  have  been  used  on  the  Continent  for 
a  long  time,  but  one  disadvantage  has  been  that  the 
message  was  written  on  a  tape  or  ribbon  of  paper. 

There  is  great  activity  in  this  line  of  invention  at 
present.  One  inventor  uses  a  typewriter  to  prepare 
a  perforated  tape,  which  is  run  through  the  transmitter, 
operating  the  distant  receiver,  which  produces  a  similar 
perforated  tape,  which,  in  turn,  is  run  through  a  special 
typewriter,  producing  the  message  in  letter  form.  This 


ENORMOUS   TELEGRAPH   BUSINESS 

may  seem  a  somewhat  roundabout  method,  but  the  object 
is  to  gain  a  high  rate  of  speed  in  transmission  over  the 
line.  Other  inventors  are  at  work  with  type  wheels  in  the 
receiving  instruments  to  be  controlled  by  a  distant  trans- 
mitter, having  keys  similar  to  a  typewriting  machine ; 
the  message  to  be  in  page  form,  ready  for  delivery.  This 
is  really  equivalent  to  having  the  keys  of  a  typewriter  at 
one  end  of  the  line  wire  while  the  types  are  at  the  distant 
end.  There  seems  little  doubt  we  shall  some  day  receive 
our  telegrams  in  typewritten  form,  just  as  produced  by 
the  telegraph  instrument. 

There  is  an  invention  of  long  standing  by  which  one 
may  write  in  ordinary  hand,  using  a  pen  connected  to 
some  electrical  mechanism,  and  a  pen  in  the  distant 
receiver  will  exactly  imitate  every  movement  of  the  pen 
in  the  transmitter,  so  that  one  may  write  a  letter  or 
sketch  a  picture  on  the  transmitter,  and  a  reproduction 
will  simultaneously  appear  at  the  distant  receiver.  This 
apparatus  is  most  ingenious,  and  would,  no  doubt,  have 
come  into  general  use  for  private  lines,  but  for  the  advent 
of  the  telephone. 

The  telegraph  business  has  grown  to  an  enormous 
extent.  In  Great  Britain  alone  there  were  ninety-three 
millions  of  telegrams  passed  over  the  wires  in  the  year 
1903,  while  the  United  States  of  America  followed  closely 
with  ninety-one  millions;  France  and  Germany  each 
handling  about  half  as  many,  while  Russia  and  Japan 
despatched  nineteen  and  seventeen  millions  respectively. 
But  for  the  growth  of  the  telephone  system  there  is  no 
doubt  these  totals  would  have  been  much  greater  by  this 
time.  However,  taking  the  grand  total  of  the  six 

72 


TELEGRAPH  v.   TELEPHONE 

countries  above  mentioned,  one  finds  that  these  countries 
among  them  handle  about  one  million  telegrams  every 
day  of  the  year,  omitting  Sundays. 

The  total  of  telegrams  handled  by  the  British  Post 
Office  in  1904  was  about  three  million  less  than  in  the 
previous  year,  and  no  doubt  one  of  the  main  causes  of 
this  decline  has  been  the  rapid  increase  of  telephonic 
communication. 

While  Great  Britain  leads  in  telegraphic  messages,  it 
comes  far  behind  with  its  telephone  total.  In  the  United 
States  over  five  thousand  millions  of  telephone  messages 
have  been  exchanged  in  one  year,  so  that  for  every  telegram 
despatched  in  America  fifty  telephone  conversations  took 
place.  There  is  not  the  least  probability  of  the  tele- 
graph being  ultimately  eclipsed  by  the  telephone  for  long- 
distance work,  but  great  changes  will  doubtless  take  place 
within  the  next  generation,  and  it  may  be  that  the  tele- 
graph will  become  the  usual  means  of  transmitting 
ordinary  business  correspondence  at  a  very  low  rate. 


CHAPTER  VIII 
TELEGRAPHING    ACROSS    THE    SEA 

Early  attempts  to  lay  submarine  cables— A  bold  proposal — The  first 
Atlantic  cable — A  long  chapter  of  accidents — Success  and  failure — 
The  Great  Eastern's  task— A  search  for  a  lost  cable — How  the 
messages  are  signalled— A  wondrously  sensitive  instrument— How 
cables  become  faulty— How  faults  are  located— Early  prices  for 
cable  messages — A  cable  behaves  quite  differently  from  a  bare 
wire — A  young  man  reads  a  prophecy  in  the  fulfilment  of  which 
he  is  afterwards  destined  to  take  a  prominent  part. 

IT  is  a  comparatively  easy  thing  to  connect  two  places 
on  land  together  by  means  of  a  wire  stretched  be- 
tween poles  right  across  the  country,  but  to  attempt 
to  connect  two  places  with  a  vast  ocean  between  is  a 
much  more  difficult  task.  In  the  early  days  of  land 
telegraphy  many  experimenters  tried  to  lay  an  insulated 
wire  under  water,  but  with  varying  and  short  -  lived 
success.  After  one  almost  complete  failure  in  attempt- 
ing to  connect  Dover  with  Calais,  which  exploit  was 
generally  accounted  a  mad  freak,  it  required  a  sanguine 
man  to  raise  a  sum  of  £15,000  to  make  a  second  trial. 
It  is  to  the  credit  of  Mr.  T.  R.  Crampton,  an  eminent 
railway  engineer,  that  he  not  only  raised  the  sum  in 
1850,  but  that  he  subscribed  half  of  the  required  amount 
out  of  his  private  purse.  It  was  not  without  difficulty 

74 


FIRST  ATLANTIC  CABLE 

that  even  this  comparatively  short  cable  was  laid,  but 
the  success  that  attended  it  gave  promise  of  greater 
achievements. 

Further  advance  was  not  to  be  all  plain  sailing,  for 
three  different  attempts  to  connect  England  and  Ireland 
only  ended  in  sinking  expensive  cables  that  were  quite 
unable  to  withstand  the  strong  tidal  currents,  etc.  A 
fourth  attempt  with  a  much  heavier  cable  fortunately 
proved  successful. 

It  was  soon  boldly  proposed  that  an  attempt  should  be 
made  to  span  the  great  Atlantic  Ocean,  and  thus  connect 
Europe  with  America.  This  was  indeed  a  bold  sugges- 
tion, for  the  laying  of  all  previous  cables  was  mere  child's 
play  when  compared  with  the  spanning  of  a  great  open 
ocean,  measuring  at  places  nearly  three  miles  in  depth. 
It  is  somewhat  surprising  that  there  was  not  much 
difficulty  in  raising  a  capital  of  £350,000  towards  the 
laying  of  an  Atlantic  cable,  which  must  needs  have  been 
pretty  much  of  an  experiment. 

It  is  difficult  even  to  conceive  the  magnitude  of  the 
task  of  manufacturing  a  cable  over  2,500  miles  in  length, 
but  some  idea  of  the  stupendous  work  may  be  obtained 
by  a  mere  statement  of  the  fact  that  this  cable,  which 
was  made  of  several  strands  of  copper  wire  for  the  con- 
ductor with  a  substantial  insulation  of  gutta-percha  and 
an  outer  protection  of  iron  wires  making,  as  it  were,  an 
iron  rope  with  an  insulated  copper  core,  required  a  total 
length  of  wire  more  than  sufficient  to  stretch  from  the 
earth  to  the  moon.  However,  the  manufacture  and  also 
the  stowing  away  of  the  cable  into  the  holds  of  one 
British  and  one  American  man-of-war  were  easy  tasks  as 

75 


A  LONG  CHAPTER  OF  ACCIDENTS 

compared  with  the  difficulties  in  laying  the  cable  safely 
on  the  bed  of  the  great  ocean. 

Having  left  one  end  of  the  cable  on  the  Irish  coast  the 
great  American  warship  steamed  slowly  away,  but  before 
a  paltry  five  miles  of  the  cable  had  been  paid  overboard 
the  cable  caught  in  some  of  the  paying-out  apparatus 
and  parted.  The  lost  end  was  with  difficulty  found  by 
tracing  the  cable  from  the  shore  end.  After  splicing  this 
to  the  rest  of  the  cable  all  went  well  for  a  few  days,  but 
once  more  the  cable  snapped,  leaving  some  380  miles  at 
the  bottom  of  the  ocean,  the  broken  end  going  to  a 
depth  of  2,000  fathoms.  The  ships  had  to  return  home 
and  abandon  the  lost  cable,  but  ultimately  recovered  fifty 
miles  of  the  shore  end. 

In  the  following  year  (1858)  the  great  ships  steamed 
off  once  more  with  some  3,000  miles  of  precious  cable, 
and  with  improved  machinery  for  paying  out.  Previous 
to  starting  on  this  second  voyage  the  steamers  had  made 
extensive  experiments  in  laying  some  defective  cable  in 
the  Bay  of  Biscay,  in  order  to  test  the  new  machinery  and 
give  practice  to  those  responsible  for  its  control.  On 
this  occasion  it  was  decided  that  both  steamers  should 
begin  at  the  middle  of  the  ocean,  and  after  splicing  the 
two  cables  together  pay  out  in  the  directions  of  the  two 
shores.  This  plan  was  proposed  at  the  very  outset  by 
the  engineer-in-chief,  but  was  objected  to  by  the  elec- 
tricians, who  preferred  that  one  steamer  should  lay  half 
of  the  cable  from  the  Irish  shore  to  mid-ocean,  where  the 
other  ship  was  to  join  up  its  cable  and  lay  the  second 
half  to  the  American  shore.  However,  it  was  decided  to 
try  the  mid-ocean  start  this  time,  but  before  reaching 

76 


A  LONG  CHAPTER  OF  ACCIDENTS 

mid-ocean  the  British  war  vessel  was  almost  lost  in  a 
storm,  owing  to  the  great  dead  weight  she  carried. 
Having  met  and  spliced  the  cables,  the  two  ships  had  not 
gone  many  miles  paying  out  the  cable  when  it  broke,  and 
another  start  had  to  be  made. 

During  the  laying  of  the  cable  electrical  communica- 
tion was  kept  up  between  the  ships  through  the  whole 
length  of  the  cable,  and  after  some  forty  miles  had  been 
paid  out  in  this  second  attempt  the  electrician  (late 
Lord  Kelvin)  reported  to  those  on  deck  that  another 
break  had  occurred,  apparently  at  some  distance  from  the 
steamer.  Another  meeting  in  mid-ocean,  another  splicing 
of  the  remaining  cables,  and  the  two  vessels  again  made 
off  for  the  distant  shores,  but  after  each  steamer  had 
laid  over  one  hundred  miles  of  cable  yet  another  break 
occurred.  At  the  last  mid-ocean  meeting  it  had  been 
arranged  that  if  a  further  break  occurred  before  a  hundred 
miles  of  cable  had  been  paid  out  from  the  start  the 
ships  should  once  more  meet,  but  if  the  cable  snapped 
after  they  had  passed  one  hundred  miles  they  should  each 
make  for  Queenstown.  Those  on  board  the  British  man- 
of-war  decided  to  return  to  mid-ocean,  as  the  break 
occurred  only  a  few  miles  beyond  the  limit,  but  after 
hanging  about  the  meeting-place  for  some  days  they 
found  that  the  other  vessel  had  evidently  kept  to  the 
exact  instructions,  so  that  there  was  nothing  for  it  but 
to  return  home  too. 

This  was  very  disheartening,  but  it  is  most  fortunate 
that,  though  the  chairman  of  the  Cable  Company  urged 
the  abandonment  of  the  whole  scheme  and  the  realising 
of  what  cable  was  left,  it  was  ultimately  decided  that 

77 


SUCCESS   AND  FAILURE 

another  attempt  should  yet  be  made ;  and  the  vessels  set 
off  for  the  agreed  dot  upon  their  respective  charts. 

On  this  occasion,  after  many  narrow  escapes  and  much 
anxiety,  the  two  ends  of  the  cable  were  safely  brought 
to  the  respective  shores  from  the  splice  in  mid-ocean, 
amidst  much  rejoicing  on  both  sides  of  the  Atlantic  in 
the  August  of  1858. 

After  congratulatory  messages  had  been  despatched 
and  reciprocated,  the  first  piece  of  public  news  sent  over 
the  cable  was  information  from  New  York  of  a  collision 
between  two  of  the  Cunard  mail  steamers,  compelling  the 
outgoing  vessel  to  put  back  to  port.  The  message  in- 
formed the  friends  in  Europe  that  no  lives  were  lost,  and 
so  spared  them  the  anxiety  that  would  otherwise  have 
been  caused  by  the  non-arrival  of  the  great  steamer  at 
her  appointed  time. 

Among  the  early  messages  was  one  from  the  British 
Government  to  the  generals  of  two  British  regiments 
stationed  in  Canada.  Orders  had  been  sent  by  mail  that 
the  regiments  were  to  return  at  once  to  England  and 
proceed  to  the  East  to  help  in  suppressing  the  Indian 
Mutiny,  but  meantime  the  mutiny  was  quelled,  so  that 
there  was  no  need  of  the  assistance  of  these  troops. 
The  next  mail  would  have  been  too  late  to  cancel  the 
orders,  but  by  means  of  the  new  cable  instructions  were 
immediately  sent,  thus  saving  a  sum  of  some  fifty  or 
sixty  thousand  pounds. 

The  troubles  of  the  Cable  Company  were  not  all  over 
yet,  for  very  soon  the  long  submarine  conductor  began  to 
show  signs  of  giving  out.  The  messages  became  less  and 
less  distinct  until  they  grew  so  faint  that  the  signals  were 

78 


SEARCH   FOR  A   LOST  CABLE 

confused,  and  ultimately  died  away  altogether.  During 
its  short  life  the  cable  had  carried  between  seven  and 
eight  hundred  messages,  but  if  a  cable  was  only  to  last  a 
short  time  it  would  not  pay  to  lay  one. 

After  much  consultation  and  experimenting,  it  was 
determined  that  the  cause  of  the  failure  was  the  use  of 
too  great  intensity  of  current.  Instead  of  merely  using 
a  battery  as  had  been  done  in  testing  on  board  ship,  the 
electricians  had  greatly  intensified  the  current  by  means 
of  large  induction  coils. 

It  was  with  difficulty  that  after  a  lapse  of  some  years 
new  capital  was  raised  to  make  another  attempt  in  1865. 
Past  experience  helped  in  the  manufacture  of  a  better 
cable,  both  as  regards  strength  and  conductivity.  It 
was  on  this  occasion  that  the  Great  Eastern,  which  had 
proved  a  white  elephant  for  trading  purposes,  having 
lain  idle  for  the  greater  part  of  ten  years,  was  employed 
to  carry  the  whole  of  the  new  cable  and  to  commence 
laying  it  from  Britain  to  America.  After  several  delays, 
owing  to  faulty  parts  in  the  cable,  a  break  occurred 
which  proved  a  serious  trouble.  Several  attempts  were 
made  to  recover  the  broken  end,  which  was  discovered 
and  hooked  three  different  times,  but  it  was  found  im- 
possible to  get  it  raised,  so  that  the  Great  Eastern  had  to 
return  home  with  her  task  unaccomplished. 

Nothing  daunted,  the  company  raised  new  funds,  not 
only  to  lay  another  cable,  but  to  attempt  the  completion 
of  the  lost  one  also.  Both  of  these  attempts  proved  suc- 
cessful in  the  following  year. 

It  would  seem  almost  ridiculous  to  attempt  to  find  the 
end  of  a  lost  cable  in  the  middle  of  a  vast  ocean,  but  as 

79 


HOW   MESSAGES  ARE   SIGNALLED 

particular  note  of  the  longitude  and  latitude  of  the  place 
had  been  made  at  the  time  of  the  loss,  the  searchers  were 
able  to  get  somewhere  near  the  lost  treasure.  With 
patience,  the  cable  was  at  last  found,  but  there  were 
many  sore  disappointments  before  it  was  brought  to  the 
very  surface,  and  even  then  it  slipped  away  like  a  living 
sea-monster  more  than  once,  until  the  task  began  to  seem 
quite  hopeless.  On  one  occasion  there  was  much  rejoicing 
when  the  end  of  the  precious  cable  was  apparently  brought 
on  deck,  but  one  can  imagine  the  feelings  of  the  patient 
toilers  when  it  was  discovered  that  they  had  merely 
hooked  a  few  odd  miles  of  faulty  cable  which  had  been 
used  in  some  experiments.  After  many  failures,  and  just 
when  about  to  give  up  in  despair,  the  cable  was  at  last 
brought  on  board  from  some  shallower  depth;  and  the 
sense  of  relief  must  have  been  great  when  the  electrical 
tests  proved  it  to  be  still  in  a  working  condition. 

At  the  shore  end  those  in  charge  must  have  almost 
given  up  all  hope,  but  when  in  the  quietness  of  a  Sunday 
morning  the  watcher  at  the  receiving  instrument  saw 
apparent  signs  of  life,  how  eagerly  would  he  decipher  the 
signals  and  carefully  note  the  message,  which  read : — 
"  Ship  to  Shore  ;  I  have  much  pleasure  in  speaking  to  you 
through  the  1865  cable.  Just  going  to  splice."  Those 
who  had  secured  the  lost  cable  would  feel  justly  proud 
when  they  succeeded  in  completing  the  whole  length. 

It  was  now  clear  that  ocean  telegraphy  had  come  to 
stay.  Many  other  cables  were  laid  from  place  to  place, 
and  the  cable  companies  of  to-day  do  not  hesitate  to 
sink  half  a  million  pounds  sterling  in  a  single  cable 
across  the  Atlantic,  while  a  whole  fleet  of  cable-repair- 

80 


A  SENSITIVE   INSTRUMENT 

ing  vessels  is  constantly  stationed  in  various  parts  of  the 
world. 

The  telegraph  apparatus,  and  even  the  delicate  relay,  as 
used  on  land  wires,  are  much  too  heavy  to  be  used  on 
long  submarine  cables,  so  that  it  was  found  necessary  to 
have  a  much  more  sensitive  receiver,  although  for  short 
cables  (such  as  across  the  Irish  Channel,  etc.)  ordinary 
morse-inkers  are  worked  by  the  Post  Office.  It  was  by 
the  inventive  brain  of  Professor  William  Thomson  (late 
Lord  Kelvin)  that  a  suitable  instrument  wa£  devised.  The 
principle  upon  which  this  works  is  very  simple,  and  is  in 
point  of  fact  the  same  as  already  described  in  the  needle 
telegraph.  It  will  be  remembered  that  the  current  pass- 
ing in  a  coil  of  wire  caused  a  magnetic  needle  to  swing 
round.  In  this  more  delicate  apparatus  a  very  tiny  magnet 
is  suspended  by  a  silk  fibre,  inside  a  small  coil  of  very  fine 
wire ;  but  as  a  small  movement  of  this  little  magnet  could 
not  be  easily  seen,  there  is  attached  to  it  a  tiny  mirror, 
which  along  with  the  magnet  weighs  only  about  a  single 
grain.  A  lamp  throws  a  fine  ray  of  light  through  a  slot 
in  a  screen,  and  this,  falling  upon  the  mirror,  may  be 
reflected  upon  the  wall  or  upon  a  graduated  scale.  By 
this  ingenious  method  a  very  small  turning  of  the  tiny 
magnet  gives  a  large  motion  to  the  spot  of  light,  as  every 
boy  who  has  annoyed  his  neighbours  with  a  small  sun- 
reflector  will  well  understand. 

At  the  present  time  there  is  a  story  going  the  round  of 
daily  papers  and  magazines  to  the  effect  that  the  use  of  a 
small  mirror  was  suggested  to  Lord  Kelvin  by  his  eyeglass 
falling  and  dangling  before  him;  but  I  think  we  may 
safely  label  this  story  "  pure  fiction "  without  referring 
F  81 


A  SENSITIVE   INSTRUMENT 


the  matter  to  his  lordship,  for  of  all  men  Lord  Kelvin 
would  be  well  versed  in  every  previous  electrical  device, 
and  there  is  on  record  an  early  telegraph  by  two  German 
experimenters  in  which  they  used  a  mirror  to  indicate  the 
turning  of  a  magnet,  though  it  was  a  very  clumsy  affair. 
This  fact  does  not  detract  from  Lord  Kelvin's  invention, 
the  beauty  of  which  is  its  great  sensitiveness,  and  the 
suggestion  to  use  the  reflected  ray  of  light  to  point  out 
the  movement  of  the  tiny  magnet  instead  of  attaching  a 
pointer  or  indicator  to  the  magnet  and  thus  increasing  its 
weight.  This  instrument  is  known  as  a  "  mirror  galvano- 
meter," and  is  used  for  making  delicate  tests. 

The  same  great  genius  devised  a  means  by  which  the 
movements  of  the  little  magnet  might  record  the  signals. 
The  construction  of  this  instrument,  which 
is   termed   a   siphon   recorder,   is   somewhat 
different  from  the  mirror  galvanometer  just 
described,  but  the  principle  is  the  very  same. 
A   very  fine   glass   tube   has   one   end  dip- 
ping into  a  small  well  of  ink  and  the  other 
end  close  to  a  paper  ribbon,  which  passes 
along  by  clockwork.     This   little   tube  acts 
as  a  siphon  to  carry  the  ink  from  the  well  to 
the  paper,  and  it  is  operated  by  the  little 
magnet,  so  that  it  is  drawn  to  the  right  or 
left  hand  in  sympathy  with  the  movements 
of  the  magnet.     In  this  way  a  record  of  the 
signals  is  taken,  as  shown  in  Fig.  7,  in  which  the  right 
and  left  movements  are  easily  discerned  on  either  side  of 
the  dotted  line. 

The  alphabet  is  the  same  as  in  the  simple  needle  tele- 

82 


B 


FIG.  7 


HOW   CABLES   BECOME  FAULTY 

graph,  so  that  the  letter  A,  which  is  indicated  by  the 
needle  falling  first  to  the  left  and  then  to  the  right,  will 
appear  on  the  cable  paper  as  shown  in  the  accompanying 
diagram. 

It  is  interesting  to  note  that  in  order  to  get  the  ink 
to  flow  freely  through  so  fine  a  tube,  the  inventor  found 
it  necessary  to  electrify  the  ink.  The  idea  no  doubt  was 
suggested  by  a  discovery  that  was  made  in  1780,  that 
water  issuing  from  a  nozzle  in  drops  would  flow  in  a 
stream  if  electrified.  At  a  later  date  it  was  found  that,  if 
the  siphon  was  given  a  vibratory  motion,  the  same  result 
was  obtained. 

Returning  to  the  subject  of  the  long  submarine  cables 
connecting  distant  lands,  it  will  be  quite  evident  that 
after  a  cable  is  safely  laid  at  the  bottom  of  the  great  deep 
it  may  not  be  in  a  very  stable  condition.  If  a  cable  were 
to  be  laid  across  the  country  from  a  balloon  there  would 
probably  be  many  hilly  places  where  the  cable  would  not 
touch  the  ground,  but  would  stretch  from  one  hillside 
across  a  valley  to  another  hill ;  and  so  it  happens  in 
similar  fashion  that  there  are  many  rough  places  at  the 
bottom  of  the  ocean  where  the  cable  stretches  across  a 
valley,  and  at  such  points  it  may  easily  become  strained 
and  ultimately  broken  by  a  rubbing  friction  caused  by 
ocean  currents,  etc.  Then,  again,  the  cable  may  be 
slowly  destroyed  by  chemical  action  in  certain  waters,  or 
serious  injury  may  be  caused  by  submarine  earthquakes, 
or,  as  has  sometimes  happened,  a  cable  has  suffered  from 
attacks  made  upon  it  by  some  sea  monster.  On  several 
occasions  the  teeth  of  such  monsters  have  been  found 
embedded  in  the  cable  coverings  at  places  where  faults 

83 


HOW  FAULTS  ARE  LOCATED 

occurred,  and  at  least  twice  has  a  great  whale  been  found 
entangled  with  a  cable. 

It  would  be  a  very  serious  matter,  when  a  fault  occurs 
and  signals  become  weak  or  altogether  cease,  if  the  repair- 
ing squad  had  to  make  an  examination  of  the  whole 
cable  in  order  to  locate  the  fault.  Such  a  task  would 
indeed  be  a  thousand  times  worse  than  looking  for  a 
needle  in  a  haystack,  but  fortunately  for  the  success  and 
the  economy  of  cable  companies,  it  is  possible  to  find  out 
in  a  very  simple  way  exactly  whereabouts  the  fault  has 
occurred. 

Every  wire  or  cable  offers  a  certain  amount  of  resistance 
to  the  passage  of  an  electric  current  according  to  the  size 
and  quality  of  the  wire,  and  a  particular  note  is  kept  of 
the  exact  amount  of  resistance  a  mile  length  of  each  cable 
offers.  If  a  cable  breaks  at  any  point  then  the  current 
gets  to  earth  at  that  place,  and  by  passing  a  current  into 
the  cable  it  can  be  seen  by  a  galvanometer  how  much 
resistance  is  being  offered  to  the  current,  for  the  smaller 
the  resistance  the  more  current  will  flow.  Having  found 
the  total  resistance  to  the  current,  it  is  easy  to  calculate 
the  length  of  cable  that  offers  such  resistance,  and  if  it  be 
found  to  be  equal  to  the  resistance  of  110J  miles  of  cable, 
then  it  is  known  that  the  break  has  occurred  at  that 
distance  from  the  shore  end,  while  the  chart  of  the  route 
will  give  the  latitude  and  longitude  of  the  particular 
place  where  the  broken  end  must  be  lying. 

In  the  Atlantic  Ocean  alone  there  are  sunk  some 
40,000  miles  of  cables,  giving  constant  employment  to  a 
very  large  staff  of  workers,  clerks,  etc. 

Commencing  with  a  charge  of  £20  for  twenty  words, 

84 


CABLE  AND  BARE  WIRE 

the  price  soon  came  down  fifty  per  cent.,  and  then  to 
thirty  shillings  for  ten  words,  at  which  figure  it  stood  for 
a  long  time.  In  1872  the  price  stood  at  four  shillings  per 
word,  but  thanks  to  increased  business  and  competition 
we  can  now  afford  to  cable  very  ordinary  business  or 
private  messages  at  a  rate  of  one  shilling  per  word,  and  if 
the  rate  should  drop  to  sixpence  the  public  on  both  sides 
of  the  Atlantic  will  no  doubt  take  a  correspondingly 
increased  advantage. 

One  great  difficulty  in  telegraphing  across  the  seas  is 
that  an  insulated  cable  behaves  quite  differently  from  an 
ordinary  bare  telegraph  wire.  The  cable  becomes  charged 
something  like  a  Leyden  jar,  and  thus  retards  the  flow  of 
the  current,  so  that  special  condensers  require  to  be  used 
to  assist  the  current. 

The  automatic  transmitters  described  in  the  preceding 
chapter  are  also  used  on  cables,  but  not  so  much  for 
speed  as  to  obtain  a  regularity  of  signals. 

Lord  Kelvin's  connection  with  the  pioneer  cables  is  well 
known,  but  I  have  been  very  much  interested  to  learn 
from  Dr.  David  Murray  that  he  remembers  being  present 
at  a  meeting  of  the  British  Association,  held  at  Glasgow  in 
1840,  at  which  a  model  of  Ponton's  Galvanic  Telegraph 
was  exhibited,  the  description  of  which  closed  with  the 
sentence :    "  The    further    improvement    of   this  instru- 
ment, and  a  more  familiar  acquaintance  with  its  use,  may 
ultimately  lead  to  connections  being  made  between  the 
most  distant  countries  in  the  world  for  the  transmission  of 
intelligence;  and  posterity  may  perhaps  witness  the  receipt 
of  news  from  India,  by  means  of  galvanic  telegraph,  in 

85 


PROPHECY  FULFILLED 

as  many  minutes  as  there  are  weeks  now  occupied  in  the 
conveyance  of  a  despatch." 

It  is  remarkable  that  this  apparently  long  look  ahead 
was  fulfilled  for  that  generation,  and  that  a  young  man, 
William  Thomson,  of  Glasgow,  who  was  present  at  that 
meeting,  became  the  chief  actor  in  this  great  historical 
event. 

While  the  name  of  Sir  William  Thomson  (afterwards 
Lord  Kelvin)  stands  out  very  prominently  in  connection 
with  the  first  Atlantic  cables,  it  should  be  noted  also  that 
a  great  deal  of  the  success  in  laying  the  cables  was  due  to 
the  ingenuity  and  skill  of  the  late  Sir  Charles  Tilston 
Bright,  who  designed  and  supervised  the  working  of  the 
paying-out  machinery.  As  engineer-in-chief,  Bright  had 
many  difficulties  to  contend  with,  and  although  only 
twenty-six  years  of  age  at  that  time,  he  overcame  all 
these  troubles  which  many  of  the  leading  men  of  the  day 
said  were  insurmountable. 


CHAPTER  IX 

SOME  EARLY  ATTEMPTS  AT 
TELEGRAPHY 

An  ingenious  surgeon  in  Scotland  invents  an  electric  telegraph  150 
years  ago— Other  inventors— The  great  difficulty  these  early 
experimenters  had  to  contend  with — The  beginnings  of  the 
practical  telegraph — Thirty  connecting  wires  reduced  to  one  single 
wire— A  very  easily  satisfied  British  Government. 

ONE  would   not   expect   to  find  any  attempt  at 
telegraphy  in  the  days  when  man's  only  knowledge 
of  electricity  was  its  wild  and  sudden  discharge 
from  an  electrical  machine,  and  yet  there  exist  on  record 
several  very  interesting  attempts  in  those  days  prior  to 
Volta's  taming  of  electricity  into  a  peacefully  tractable 
current,  as  we  have  it  from  batteries. 

It  is  evident  that  some  attempts  to  transmit  intelli- 
gence by  electricity  were  made  as  far  back  as  the  middle 
of  the  sixteenth  century,  although  the  records  of  these 
are  somewhat  vague,  and  appear  to  have  been  carried  out 
by  some  monks  in  a  German  monastery. 

In  the  Scots  Magazine  of  February  1st,  1753,  there 
appeared  a  letter  describing  a  practical  electric  telegraph 
worked  by  a  primitive  electrical  machine.  The  letter  was 
merely  signed  UC.  M.,"  and  was  written  from  Renfrew, 
a  small  town  on  the  River  Clyde,  a  few  miles  below 
Glasgow. 

87 


AN   INGENIOUS   SURGEON 

The  one  property  of  electricity  with  which  this  in- 
genious writer  would  be  most  familiar  was  doubtless  the 
attraction  between  an  electrified  body  and  any  light 
object  placed  near  it,  and  so  it  occurred  to  him  that  if  he 
could  charge  a  long  connecting-wire  between  two  places, 
then  the  distant  end  would  attract  a  small  piece  of  paper 
placed  close  to  it.  Having  determined  that  this  could 
be  done,  he  set  up  twenty-six  separate  wires,  connecting 
his  dwelling  to  a  distant  cottage  in  the  village.  The 
wires  were  supported  on  insulators  at  short  distances 
apart,  being  fixed  at  each  of  the  two  distant  ends  in 
a  bar  of  solid  glass,  leaving  about  six  inches  of  wire 
extending  beyond  the  glass  fixture.  These  six-inch  ends 
were  stiffened,  so  that  if  depressed  they  would  spring 
back  to  their  horizontal  position.  These  free  ends  were 
then  placed  immediately  above  the  glass  cylinder  of  an 
electrical  machine,  so  that  while  the  machine  was  "ex- 
cited"" by  rotating  it,  any  of  these  twenty-six  ends  could 
be  pressed  down  to  touch  the  cylinder,  and  thus  the 
whole  length  of  this  particular  wire  would  receive  a  charge 
of  electricity. 

At  a  point  close  to  where  each  wire  entered  the  solid 
glass  fixture  the  inventor  suspended  a  short  piece  of  wire 
with  a  metal  ball  at  its  extremity,  there  being,  therefore, 
twenty-six  separate  balls.  Immediately  under  each  ball 
he  placed  a  small  piece  of  paper  bearing  one  letter  of  the 
alphabet  upon  it.  This  arrangement  was,  of  course, 
carried  out  at  both  ends  of  the  line  wire.  To  signal  the 
letter  A  the  operator,  having  set  the  electrical  machine 
in  motion,  would  take  a  piece  of  solid  glass  in  his  hand, 
and,  depressing  the  end  of  the  first  wire  till  it  touched 

88 


AN  INGENIOUS  SURGEON 

the  cylinder,  he  would  charge  the  whole  of  that  wire  so 
that  the  suspended  metal  ball  at  each  end  would  attract 
its  particular  paper  marked  A.  The  person  at  the  re- 
ceiving end  would  take  note  of  A,  while  the  operator 
would  see  by  the  attraction  of  A  at  his  own  end  that  the 
wire  had  been  sufficiently  charged.  In  the  same  way  all 
the  twenty-six  letters  of  the  alphabet  could  be  signalled 
in  any  desired  order,  thus  enabling  intelligible  messages 
to  be  sent.  The  inventor  says  that  the  letters  "  were  con- 
trived to  fall  back  into  their  proper  places,"  so  he  may 
possibly  have  had  a  small  glass  division  for  each  letter  to 
rise  and  fall  within. 

The  inventor  also  suggested,  among  other  arrange- 
ments, that  each  of  the  little  metal  balls  might  by  attrac- 
tion be  made  to  strike  against  a  little  gong,  there  being 
twenty-six  gongs  of  different  sounds,  and  the  person 
using  the  apparatus  would,  as  the  inventor  said,  "soon 
understand  the  language  of  the  bells."  In  this  sugges- 
tion we  have  the  first  idea  of  a  "  sounder  "  telegraph,  and 
it  is  by  sound  signals  that  most  telegraph  messages  are 
now  received. 

The  great  difficulty  in  working  any  such  apparatus  as 
that  just  described  would  be  to  prevent  the  high  tension 
charge  from  making  a  dash  to  earth  through  every  pos- 
sible means  of  escape,  and  in  this  connection  it  will  be  of 
interest  to  note  a  few  sentences  from  the  inventor's  letter. 
He  writes :  "  Some  may  perhaps  think  that  although  the 
electric  fire  has  not  been  observed  to  diminish  sensibly  in 
its  progress  through  any  length  of  wire  that  has  been  tried 
hitherto;  yet,  as  that  has  never  exceeded  thirty  or  forty 
yards,  it  may  be  readily  supposed  that  in  a  far  greater 

89 


OTHER  INVENTORS 

length  it  would  be  remarkably  diminished,  and  probably 
would  be  drained  off  in  a  few  miles  by  the  surrounding 
air.  To  prevent  this  objection,  and  save  further  argu- 
ment, lay  over  the  wires  from  one  end  to  the  other  with  a 
thin  coating  of  jeweller's  cement.  This  may  be  done  for 
a  trifle  additional  expense,  and  as  it  is  an  electric  per  se, 
will  effectually  secure  any  part  of  the  fire  from  mixing 
with  the  atmosphere.""  Here  we  have,  at  this  early  date, 
the  idea  of  an  insulated  wire  as  used  for  almost  all  elec- 
trical purposes  at  the  present  time. 

It  is  interesting  to  note  that  the  mental  picture  which 
this  ingenious  man  formed  of  electricity  was  that  of  a 
"  fire,"  which  thought  was  very  natural  owing  to  the  ap- 
pearance of  a  spark  at  any  point  where  the  electricity 
suddenly  escaped  from  one  body  to  another. 

The  late  Sir  David  Brewster  made  particular  search  to 
discover  the  history  of  this  anonymous  letter  writer, 
"C.  M.,"  and  his  efforts  met  with  a  certain  amount  of 
success.  He  first  of  all  found  out  that  a  very  clever  man 
had  lived  in  Paisley  in  1791 ;  that  he  came  from  Renfrew, 
which  is  only  a  few  miles  distant ;  and  that  it  was  re- 
ported of  this  genius  that  he  "  could  light  a  house  with 
coal  reek  (smoke),  and  make  lightning  speak  and  write." 
At  a  later  date  Sir  David  Brewster  found  that  this  man's 
name  was  Charles  Morrison,  who  was  a  native  of 
Greenock,  but  practised  for  some  time  as  a  surgeon  in 
Renfrew,  and  ultimately  became  connected  with  the 
tobacco  trade  in  Glasgow.  Morrison  was  counted  a 
wizard,  and  his  neighbours  believed  him  to  be  in  concert 
with  the  devil,  because  of  the  apparently  supernatural 
power  he  had  of  sending  messages  to  a  distant  cottage. 

90 


PRACTICAL  TELEGRAPH 

He  ultimately  went  out  to  Virginia,  U.S.,  where  he 
died. 

Another  early  form  of  telegraph  suggested  was,  that  the 
sender  and  the  receiver  should  each  have  a  good  clock, 
with  the  letters  of  the  alphabet  painted  round  the  dial, 
and  the  two  clocks  keeping  accurate  time,  the  "  second " 
hands  would  point  to  the  same  letter  on  each  dial  at  the 
same  moment.  By  a  connecting  wire  between  the  distant 
places  a  Ley  den  jar  was  made  to  spark  at  the  moment  the 
hand  was  opposite  the  letter  that  the  sender  wished  to 
telegraph,  the  receiver  also  noting  the  letter  indicated  on 
his  clock  at  the  moment  when  the  spark  occurred.  The 
first  idea  of  this  inventor  had  been  the  very  primitive 
method  of  striking,  with  some  object  in  his  hand,  upon 
the  bottom  of  a  copper  stew  pan  at  the  moment  his  clock 
was  at  the  desired  letter,  but  it  is  evident  that  this 
method  of  using  sound  could  not  have  been  extended 
to  any  great  distance.  His  subsequent  system  of  using 
the  charged  Leyden  jar  only  required  one  wire,  but 
the  difficulty  of  keeping  the  charge  to  the  wire  would 
necessarily  worry  the  inventor  if  he  tried  it  over  a 
distance. 

A  very  similar  and  better  known  invention  was 
Ronald's  Electric  Telegraph,  in  which  the  dials  of  the 
clocks  moved  round,  bringing  the  letters  of  the  alphabet 
painted  upon  them  into  view  successively  through  an 
aperture  in  a  covering  case.  When  the  desired  letter 
appeared  in  the  slot  a  signal  was  sent  by  discharging  a 
wire  at  the  end  of  which  a  pair  of  electrified  pith  balls, 
suspended  by  two  threads,  repelled  each  other  until  the 
discharge  took  place,  whereupon  they  immediately  came 

91 


ELABORATE  TELEGRAPHS 

together  by  gravity.  By  this  primitive  method  the 
words  of  the  message  were  slowly  built  up. 

After  Volta's  introduction  of  batteries  the  idea  of 
electric  telegraphy  became  more  practicable.  While 
these  two  last-mentioned  experiments  were  carried  out 
with  only  one  connecting  wire,  yet  it  was  a  long  time 
before  inventors  could  dismiss  from  their  minds  the  idea 
that  a  reliable  telegraph  would  require  a  great  number 
of  connecting  wires.  Even  one  of  the  greatest  French 
scientists,  Ampere,  suggested  an  instrument  which  re- 
quired as  many  as  thirty  connecting  wires,  and  under  the 
end  of  each  there  was  to  be  placed  a  small  magnetic 
needle. 

A  few  years  later  a  German  professor  proposed  putting 
the  thirty  little  magnets  inside  as  many  coils  instead  of 
merely  under  the  single  wires ;  by  this  means  the  effect 
of  the  current  on  the  magnet  was  greater.  An  instru- 
ment of  this  kind  was  exhibited  at  the  Royal  Institution 
of  London,  in  1830,  in  which  telegraph  twenty- six 
wires,  coils,  and  magnets  were  used.  It  was  several 
years  before  anyone  suggested  that  one  wire  with  a 
single  coil  and  magnet  would  serve  the  purposes  of 
signalling. 

To  give  even  an  abstract  of  all  the  early  inventions  in 
telegraphy  would  occupy  a  good  deal  of  space,  although 
every  inventor  who  was  bold  enough  to  approach  the 
Government  of  his  day  regarding  his  invention  received 
the  somewhat  discouraging  reply  that  "telegraphs  of 
any  kind  other  than  those  now  in  use  are  entirely  un- 
necessary, as  the  Government  are  fully  satisfied  with  the 

92 


SATISFIED  BRITISH  GOVERNMENT 

semaphore  system.""  How  would  the  Government  of  to- 
day feel  if  instead  of  the  electric  telegraph  they  had  to 
be  satisfied  with  sending  intelligence  by  means  of  optical 
semaphores,  as  used  from  one  ship  to  another  at  close 
quarters  ? 


CHAPTER  X 
TELEGRAPHING   THROUGH  SPACE 

An  old-time  swindler  cornered  by  Galileo — Some  interesting  early 
experiments — Sir  William  Preece's  method— How  the  present 
system  is  worked  by  Marconi  and  others — The  importance  of 
Wireless  Telegraphy — Communicating  with  friends  far  out  on  the 
ocean— A  "  Wireless  Press  News  "  in  America — The  "  tuning  "  of 
wireless  instruments  in  order  to  obtain  secrecy — Experience  in  the 
Russo-Japanese  war — An  exciting  "wireless  "  incident— Noiseless 
wireless  music. 

THE  idea  of  telegraphing  to  a  distance  without  the 
aid  of  connecting  wires  is  by  no  means  a  new  one, 
although  its  practical  accomplishment  is  within  the 
memory  of  all. 

Some  three  hundred  years  ago  a  man  claimed  to  be 
able  to  send  wireless  messages  over  a  distance  of  thousands 
of  miles  by  means  of  two  simple  magnetic  needles  pivoted 
on  dials  around  which  the  letters  of  the  alphabet  were 
written.  No  matter  at  what  distance  the  two  dials  were 
placed  from  each  other,  the  inventor  stated  that  he  had 
only  to  move  the  one  magnetic  needle  to  point  at  any 
desired  letter,  whereupon  the  distant  needle  would  im- 
mediately turn  in  sympathy  to  the  corresponding  letter 
on  its  dial. 

When  the  inventor  was  asked  by  the  great  Italian 
astronomer  Galileo  to  show  the  instruments  at  work 

94 


EARLY  EXPERIMENTS 

across  his  room,  the  adventurer  said  that  when  close 
together  the  magnets  could  not  work;  they  required  to 
be  separated  by  a  great  distance  before  the  one  could 
influence  the  other.  Galileo  then  suggested  that  the 
inventor  should  leave  the  one  instrument  with  him,  take 
the  other  to  any  distance  he  desired,  and  then  send  him  a 
message,  but  needless  to  say  this  test  was  not  convenient 
to  the  swindler. 

Other  equally  absurd  proposals  were  made,  and  no 
doubt  believed  in  by  some,  but  it  naturally  was  not  till 
after  the  practical  electric  telegraph  was  in  use  that  any 
genuine  attempt  at  wireless  telegraphy  was  made.  Of  the 
early  experimenters  the  most  interesting  is  James  Bow- 
man Lindsay,  of  Dundee  (Scotland),  who  read  a  paper 
before  the  British  Association  in  1859  on  "  Telegraphing 
without  Wires."  It  is  interesting  to  note  that  the  illus- 
trious Michael  Faraday  and  our  great  scientist,  William 
Thomson  (Lord  Kelvin),  were  both  present  at  this 
meeting. 

Lindsay  was  a  great  genius  who  lived  for  learning.  He 
went  to  Dundee  as  science  lecturer  in  the  Watt  Institu- 
tion, and  later  he  acted  as  tutor  and  conducted  private 
classes.  While  acting  for  seventeen  years  as  teacher  in 
the  Dundee  prison  on  a  salary  of  £50  per  annum,  he 
made  many  researches  in  electricity,  constructing  his  own 
apparatus,  and  denying  himself  everything  but  the  bare 
necessaries  of  life  to  enable  him  to  follow  out  his  studies. 

In  1854  Lindsay  took  out  a  patent  "  for  transmitting 
telegraph  messages  by  means  of  electricity  or  magnetism 
through  and  across  water  without  submerged  wires,  the 
water  being  made  available  as  the  connecting  and  conduct- 

95 


WIRELESS   TELEGRAPHY 

ing  medium."  By  such  means  Lindsay  sent  telegraph 
messages  across  the  Tay  at  a  point  where  the  river  is 
about  a  mile  in  width. 

More  recently  Sir  William  Preece  worked  out  a  method 
of  wireless  telegraphy  on  the  principle  that  an  electric 
current  passing  along  one  wire  will,  at  each  make  and 
break  of  the  current,  set  up  a  similar  current  in  any  other 
wire  placed  parallel  to  it,  although  the  wires  be  placed 
miles  apart  from  each  other.  The  one  drawback  to  this 
system  is  that  the  lengths  of  these  two  parallel  wires  have 
to  be  increased  in  proportion  to  the  distance  between 
them.  Each  wire  must  be  about  equal  in  length  to  the 
distance  between  the  sending  and  receiving  stations.  It  is 
apparent  that  on  land  one  might  as  well  connect  the  two 
stations  directly  by  wire ;  but  this  system  has  proved  of 
service  on  more  than  one  occasion  where  submarine  cables 
have  broken  down,  as  between  the  English  coast  and  the 
Isle  of  Wight,  and  between  the  mainland  of  Scotland  and 
the  Island  of  Mull.  If  the  distance  from  shore  to  shore 
be  five  miles,  then  a  five-mile  line  is  run  along  each  coast. 

The  present  method  of  wireless  telegraphy,  worked  out 
by  Signer  Marconi,  is  more  truly  wireless,  and  is  on  quite 
a  different  principle. 

What  Cooke  and  Wheatstone  did  for  the  electric  tele- 
graph in  Britain,  and  Morse  in  the  United  States,  Marconi 
has  done  for  wireless  telegraphy.  None  of  these  inventors 
discovered  the  principles  that  made  telegraphy  possible, 
nor  did  they  originate  the  ideas,  but  they  brought  known 
principles  into  practical  form. 

When  each  country  nowadays  knows  exactly  what  is 
happening  in  the  other  countries  of  the  world,  it  would 

96 


WIRELESS   TELEGRAPHY 

be  surprising  if  the  whole  field  of  such  an  important 
matter  as  wireless  telegraphy  had  been  left  to  one  worker; 
the  following  are  some  of  the  most  prominent  names  in 
connection  with  wireless  work:  Marconi,  De  Forest, 
Fessenden,  Lodge -Muirhead,  Popoff,  Jackson,  Armstrong, 
Orling,  Dolbear,  Stone,  Artom,  Lepel,  and  Poulsen,  &c. 


e 


FIG.  8 

THE   PRINCIPLE   OF  WIRELESS  TELEGRAPHY 

The  current  from  the  battery  (B)  cannot  get  to  the  trembler  bell  (T) 
because  of  the  resistance  offered  by  the  coherer  (C).  When  an  electrical 
discharge  takes  place  from  the  Leyden  jar  (L),  ether  waves  go  out  and 
affect  the  filings  in  the  coherer,  allowing  the  current  to  pass  to  the  bell, 
thereby  causing  it  to  ring. 

The  general  principle  underlying  all  these  systems  may 
be  easily  understood. 

In  ordinary  telegraphy  the  sender  has  beside  him  the 
battery  and  contact  key,  while  the  line  wire  conducts  the 
G  97 


WIRELESS  TELEGRAPHY 

current  to  the  distant  telegraph  instrument.  It  will  be 
remembered  that  the  contact  key  is  merely  a  small  lever 
which  when  depressed  closes  the  circuit  and  allows  the 
current  to  flow  from  the  battery  to  the  telegraph  line. 
An  ordinary  bell-push  would  serve  the  purpose,  though 
not  so  conveniently. 

Let  us  now  imagine  the  whole  of  the  apparatus  to  be 
placed  at  the  receiving  station,  so  that  the  battery  with 
its  contact  key  and  the  telegraph  instrument  are  all  con- 
nected up  close  together  at  the  one  place.  If  the  would- 
be  sender  at  the  distant  station  could  now  by  any  means 
influence  the  contact  key  at  the  receiving  station,  making 
it  close  and  open  the  battery  circuit  at  will,  he  would 
then  be  able  to  operate  the  telegraph  instrument  and 
convey  intelligible  messages. 

It  is,  of  course,  quite  impossible  for  the  sender  to 
operate  the  contact  key  which  is  now  far  beyond  his 
reach,  but  it  is  possible  to  substitute  something  in  the 
place  of  the  contact  key  which  can  be  influenced  from  a 
distance,  even  though  the  sender  be  hundreds  of  miles 
away  from  the  telegraph  apparatus  he  desires  to  control. 

At  the  receiving  station  we  now  take  away  the  ordinary 
contact  key  and  replace  it  by  a  small  tube  or  box  of  metal 
filings,  so  that  the  current  will  have  to  pass  through  the 
filings  to  get  from  the  battery  to  the  telegraph  instrument. 
The  filings  are  only  very  loosely  packed  together,  and 
they  offer  so  much  resistance  to  the  current  that  it  cannot 
pass  through  them.  This  little  tube,  with  the  filings  in 
their  normal  condition,  is  equivalent  to  the  ordinary 
contact  key  when  open.  These  filings  are,  along  with 
every  existing  thing,  immersed  in  the  great  ocean  of 

98 


WIRELESS   TELEGRAPHY 

ether  which  pervades  all  space.  We  shall  become  more 
familiar  with  this  all-pervading  medium  in  a  later  chapter. 
For  the  present  we  shall  be  content  to  know  that  it  is 
waves  in  this  great  medium  which  provide  the  connecting 
link  between  the  transmitter  and  the  distant  receiver  in 
wireless  telegraphy. 

It  is  a  marvellous  fact  that  if  certain  ether  or  electric 
waves  fall  upon  these  little  metal  filings,  their  electrical 
resistance  to  the  current  is  so  far  diminished  that  the  cur- 
rent is  able  to  pass  through  them  and  operate  the  telegraph 
instrument.  The  tube  is  then  shaken,  the  filings  return 
once  more  to  their  ordinary  condition,  and  no  current 
can  pass.  It  will  be  observed  that  in  this  action  we  have 
an  equivalent  of  the  ordinary  telegraph  contact  key  which 
may  be  closed  and  opened  at  will.  It  only  remains  to 
produce  the  necessary  electric  waves  to  operate  it  from 
a  distance. 

An  ordinary  electric  spark  produces  waves  in  the  sur- 
rounding ether,  but  a  feeble  spark  can  give  only  a  small 
result.  By  means  of  what  is  known  as  an  induction  coil 
we  can  so  increase  the  pressure  of  an  electric  current  that 
it  will  leap  across  an  air-gap,  and  in  doing  so  it  will 
produce  a  perfect  torrent  of  spaiks.  Owing  to  this 
electrical  discharge  the  surrounding  ether  is  disturbed, 
and  waves  travel  out  in  all  directions.  It  is  remarkable 
the  distance  at  which  these  waves  may  be  detected  by  the 
little  tube  of  filings  already  described.  In  seeking  to 
describe  the  function  of  these  filings  they  were  said  to 
cohere  together  when  the  ether  waves  fell  upon  them,  and 
from  this  description  the  tube  became  known  as  the 
coherer. 

99 


WIRELESS   TELEGRAPHY 

We  may  picture  the  operator  at  the  sending  station 
switching  the  current  on  and  off  from  the  induction  coil, 
producing  torrents  of  sparks  at  will.  He  knows  that 
each  time  he  does  so  ether  waves  will  reach  the  distant 
receiver  and  cause  the  telegraph  instrument  to  record  the 
signal.  If  the  sender  wishes  to  signal  the  Morse  code 
he  will  arrange  the  duration  of  his  spark  torrents  accord- 
ingly. Three  sharp  torrents  following  close  at  each 
other's  heels  will  record  the  Morse  signal  for  the  letter  s. 
All  the  other  signals  which  are  detailed  in  Fig.  4,  page  57, 
may  be  signalled  in  the  same  way. 

As  the  coherer  tube  is  a  very  small  thing,  it  is  con- 
nected by  wires  to  metal  arms  or  "capacities,"  which 
intercept  the  ether  waves  and  conduct  the  electro-magnetic 
effect  to  the  filings  in  the  small  tube. 

It  will  be  understood  that  the  simple  apparatus  which 
I  have  described  is  descriptive  merely  of  the  general 
principle  of  wireless  telegraphy.  One  can  get  very  good 
results  with  such  apparatus  over  a  very  short  distance. 
For  long  distances  we  require  a  more  powerful  disturber 
of  the  ether  and  a  more  delicate  detector  at  the  distant 
receiving  station.  For  distances  up  to  about  two  hundred 
miles,  a  storage  battery  and  an  induction  coil  can  produce 
sufficient  disturbance  in  the  ether.  To  send  messages  to 
greater  distances  necessitates  the  wireless  station  being 
equipped  with  an  engine  and  dynamo  for  generating  the 
necessary  electric  currents  with  which  to  set  up  the 
ether  waves. 

The  receiver  may  be  some  form  of  delicate  coherer  or 
anti-coherer.  This  latter  term  signifies  that  the  receiver 
does  not  require  to  be  tapped  or  shaken  after  each 

100 


ELECTROLYTIC    DETECTORS 

impulse.  Another  form  of  detector  is  based  upon  electro- 
chemical changes  which  take  place  in  the  receiver  when 
the  ether  waves  arrive.  Those  in  this  class  are  called 
electrolytic  detectors,  while  they  might  be  described  also  as 
anti-coherers.  One  such  device  is  composed  of  a  small 
tube  similarly  arranged  to  the  ordinary  filings  tube,  but 
with  two  little  blocks  or  rods  of  tin,  between  which 
there  is  placed  a  semi-liquid  paste,  sometimes  composed 
of  alcohol  with  tin  filings  and  lead  oxide.  The  operation 
of  this  tube  is  exactly  the  reverse  of  that  of  the  metal 
filings  tube.  It  will  be  remembered  that  when  the  ether 
waves  arrived  they  enabled  the  filings  to  close  the  local 
battery  circuit.  In  the  electrolytic  detector  the  arrival 
of  the  ether  waves  stops  a  current  which  is  kept  flowing 
through  the  detector.  The  chemical  paste  in  its  normal 
condition  permits  the  battery  current  to  get  across  from 
the  one  tin  block  to  the  other,  but  the  stimulation  of 
the  ether  waves  produces  a  chemical  action  which  imme- 
diately breaks  down  this  bridge  and  stops  the  current. 
Upon  the  withdrawal  of  the  ether  waves  the  paste  returns 
at  once  to  its  normal  condition  and  allows  the  battery 
current  to  pass  again.  The  signals  are  therefore  a  sudden 
breaking  and  making  of  the  battery  circuit.  How  can 
these  signals  be  read  ? 

If  a  telephone  receiver  is  connected  to  the  tube  and 
battery,  it  will  be  very  easy  to  tell  when  the  battery 
circuit  is  broken ;  there  will  be  quite  a  loud  click  heard 
in  the  telephone.  Any  person  using  the  ordinary  tele- 
phone may  hear  a  similar  click  by  depressing  the 
telephone  hook,  or  support,  while  the  receiver  is  held 
to  the  ear.  Each  time  the  support  is  depressed  the 

101 


MAGNETIC   DETECTORS 

battery  current  is  cut  off  from  the  telephone,  and  it  is 
the  stopping  of  the  current  causing  a  sudden  change  in 
the  magnetic  field  of  the  receiver  which  produces  the 
click.  This  makes  quite  a  good  demonstration  of  how  the 
wireless  messages  are  read. 

Then  there  are  magnetic  detectors,  in  which  we  depend 
upon  the  incoming  ether  waves  affecting  a  piece  of 
magnetised  soft  iron.  The  general  principle  of  these 
will  be  understood  if  we  picture  an  endless  band  of  soft 
iron  wire  kept  in  motion  so  that  bit  by  bit  the  wire 
passes  close  to  the  poles  of  a  permanent  magnet. 
The  magnetism  of  the  wire  tends  to  change  as  it  passes 
from  the  influence  of  one  pole  to  the  other.  It  was 
discovered  that  the  time  required  for  this  change  was  very 
greatly  reduced  when  ether  or  electric  waves  fell  upon 
the  soft  iron  band.  The  magnetic  change  is  thus  rendered 
so  sudden  that  it  is  capable  of  inducing  a  momentary 
electric  current  in  a  coil  of  wire  through  which  it  passes. 
This  induced  current  is  detected  by  a  telephone  receiver 
which  is  included  in  the  circuit.  The  signals  of  the 
Morse  code  may  be  read  easily  by  such  means.  The 
operator  in  the  photograph  facing  page  94  is  reading 
wireless  signals  by  means  of  the  telephone  receiver,  which 
is  attached  to  his  head  so  that  he  may  have  the  free  use 
of  his  hands. 

There  are  many  other  interesting  devices  for  detecting 
the  arrival  of  the  ether  waves,  but  sufficient  detail  has 
been  given  to  enable  the  reader  to  understand  the  general 
principles. 

At  all  wireless  stations  there  is  some  metallic  arrange- 
ment extending  up  into  the  air  to  entrap  the  ether  waves. 

1 02 


ANTENNAE 

Such  arrangements  are  called  antennae.  Those  of  us  who 
spent  some  of  our  boyhood  leisure  hours  in  collecting 
beetles  and  other  insects  will  find  this  word  a  familiar 
one.  It  is  the  name  of  those  little  horns  or  feelers 
extending  from  the  head  of  the  insect.  With  this  picture 
in  one's  mind  one  can  see  the  appropriateness  of  the  word 
as  used  in  wireless  telegraphy. 

One  method  is  to  erect  a  simple  wire  on  a  pole.  In 
another  a  whole  network  of  wires  is  supported  from 
strong  steel  towers  built  to  a  height  of  over  two  hundred 
feet.  Sometimes  the  wires  have  been  arranged  like  a 
great  inverted  pyramid,  while  one  system  employs  a  huge 
sheet-iron  tube,  not  unlike  a  factory  chimney,  reaching  a 
height  of  over  four  hundred  feet. 

Some  of  the  most  recent  transmitters  do  not  disturb 
the  ether  by  means  of  torrents  of  sparks.  They  employ 
a  very  rapid  to-and-fro  or  alternating  current  to  set  up 
the  necessary  ether  waves.  This  method  has  been  found 
much  more  economical  in  the  power  required  for  a  given 
range  of  communication,  besides  having  other  advan- 
tages. 

In  the  first  days  of  wireless  telegraphy  we  used  to 
employ  the  picture  of  two  men  shouting  to  each  other 
across  a  distance  as  being  analogous  to  two  wireless- 
telegraph  instruments,  while  two  persons  using  an 
ordinary  air  telephone  or  speaking-tube  represented  two 
ordinary  telegraph  instruments  connected  by  a  wire.  The 
simple  analogy  of  two  men  shouting  always  suggested 
the  possibility  of  some  third  party  being  within  range 
to  hear  the  communication.  Then  again  one  knows  the 
difficulties  arising  from  a  number  of  people  all  shouting 

103 


INTERCEPTION    OF   MESSAGES 

at  the  one  time.  Similar  difficulties  were  bound  to 
present  themselves  to  the  wireless  telegraphists  when  they 
began  to  multiply  the  number  of  their  installations. 

From  the  outset  we  heard  a  good  deal  about  the  in- 
terference and  interception  of  messages.  One  ship  would 
even  pick  up  a  message  sent  out  by  some  rival  system 
of  wireless  telegraphy.  This  formed  the  most  serious 
problem  that  the  wireless  telegraphist  had  to  face.  That 
very  considerable  success  in  overcoming  this  difficulty  has 
been  made  is  demonstrated  by  the  following  facts.  One 
of  our  battleships  was  communicating  by  wireless  tele- 
graph to  another  ship-of-war  distant  from  it  about  five 
hundred  miles.  While  this  signalling  was  in  progress 
another  wireless  instrument  on  board  the  same  battleship 
was  receiving  messages  from  a  third  vessel  within  close 
range.  How  can  this  be  done  ? 

The  instruments  are  "  tuned "  so  that  they  respond  to 
each  other.  There  is  an  experiment  with  tuning-forks 
which  gives  us  a  suitable  analogy.  The  air-waves  (sound) 
from  one  tuning-fork  will  cause  a  second  fork  of  the  same 
pitch  to  vibrate  also.  Unless  the  two  forks  are  "  tuned  " 
to  the  same  pitch,  the  one  will  not  respond  to  the  other. 

We  need  not  trouble  with  the  details  of  electrical 
tuning,  except  to  point  out  that  the  transmitter  has  to 
be  arranged  to  send  out  a  definite  rate  of  ether  waves, 
while  the  receiver  is  arranged  to  respond  to  that  same 
rate  of  vibration. 

In  these  days  when  wireless  telegraphy  has  an  estab- 
lished position,  it  is  hardly  necessary  to  point  out  its 
great  value.  We  may  debate  the  probability  of  wireless 
competing  with  ordinary  telegraphy  on  land,  or  whether 

104 


TUNING   INSTRUMENTS 

it  will  ever  enter  into  serious  competition  with  ocean 
cables.  We  cannot,  however,  fail  to  see  the  very  wide 
field  which  wireless  telegraphy  has  entirely  to  itself.  It 
has  no  rivals  in  communicating  with  ships  far  out  at  sea. 
It  is  impossible  to  overestimate  the  value  of  this.  In 
addition  to  the  communication  of  ordinary  intelligence, 
there  is  the  possibility  of  a  ship  in  distress  being  able  to 
call  for  help  from  those  who  cannot  see  her.  It  is  difficult 
to  realise  what  it  would  be  to  find  ourselves  drifting  help- 
lessly out  of  the  track  of  steamers,  where  it  would  be 
impossible  to  attract  attention  to  our  disabled  ship.  Or 
picture  the  crew  upon  a  sinking  steamer,  unable  to  call 
for  any  assistance.  We  have  had  some  very  remarkable 
instances  of  large  vessels  sinking,  and  the  wireless 
operator  succeeding  in  calling  the  help  of  other  steamers  to 
which  it  would  have  been  impossible  to  signal  by  any  other 
known  means.  Indeed,  one  has  only  to  read  the  daily 
papers  to  be  impressed  with  the  great  importance  of 
being  able  to  signal  through  space  without  the  necessity 
of  connecting  wires. 

That  wireless  telegraphy  is  likely  to  prove  of  value  in 
warfare  is  appreciated  thoroughly  by  both  military  and 
naval  authorities.  The  old  proverb  that  to  be  fore- 
warned is  to  be  forearmed  still  holds  good ;  it  is  obvious 
that  the  earlier  we  can  learn  the  whereabouts  of  the 
enemy  the  more  chance  we  have  of  dealing  with  them  to 
advantage. 


105 


CHAPTER  XI 
ELECTRICITY  IN    NATURE 

Franklin  handles  the  lightning— A  Russian  professor  accidentally 
electrocuted  at  St  Petersburg— Different  kinds  of  lightning— A 
false  notion— Thunder  rain-drops  explained— How  we  may  imitate 
the  Swiss  mountain  air  in  our  hospitals— The  aurora  borealis  and 
magnetic  storms— Wonderful  electric  fish— Earthquakes  and  vol- 
canoes. 

FROM  the  earliest  ages  man  has  been  familiar  with 
the  lightnings  and  thunders  of  the  heavens,  but  if 
anyone  had   dared   to   predict  that    these   grand 
phenomena  would  be  found  to  be  due  to  the  same  source 
as  that  exhibited  by  rubbed  amber,  such  a  prophecy  would 
have  been  deemed  beyond  all  reason. 

Although  primitive  electrical  machines  were  con- 
structed about  the  middle  of  the  seventeenth  century,  it 
was  some  fifty  years  later  before  experimenters  suggested 
that  lightning  was  simply  an  immense  electric  spark ;  and 
it  was  not  till  some  forty  years  after  these  suggestions 
were  made  that  Benjamin  Franklin,  one  of  America's 
greatest  men,  was  able  to  prove  this  to  be  a  fact  by  draw- 
ing electricity  from  a  passing  thunder-cloud,  by  means  of 
a  conductor  carried  upwards  by  a  kite,  to  make  communi- 
cation with  the  cloud.  Using  a  metal  key  at  the  lower 
extremity  of  the  wetted  string,  which  acted  as  the  con- 
ductor from  the  upper  atmosphere,  Franklin  was  able  to 

to* 


By  permission  of] 


[Mr.  Taylor,  Curator  of  Paisley  Museum. 


A  vivid  Flash  of  Fork  Lightning  taken  over  House-tops.  The  lightning  discharge  is  exactly 
similar  to  the  spark  from  an  electrical  machine,  but  on  an  immensely  grander  scale.  The 
electricity  is  passing  between  a  cloud  and  the  earth. 


ACCIDENTALLY  ELECTROCUTED 

perform  all  the  known  electrical  experiments  by  charging 
bodies  from  this  key. 

Franklin  had  made  known  his  intention  of  carrying  out 
such  experiments,  and  news  of  these  particulars  having 
reached  France,  the  experiments  were  there  successfully 
carried  out  prior  to  Franklin's  demonstration  in  America. 

When  Franklin  had  succeeded  in  drawing  an  electric 
charge  from  a  thunder-cloud,  it  occurred  to  him  that  it 
would  be  possible  to  rob  these  clouds  of  their  charges  and 
thus  prevent  them  discharging  to  earth  through  high 
towers,  etc.,  which  were  so  often  seriously  damaged  when 
"struck"  by  lightning.1'  In  this  way  we  came  to  have 
lightning  conductors  attached  to  high  buildings. 

It  is  amusing  to  read  that  at  that  time  (the  summer  of 
1756)  a  German  scientist  prevailed  upon  a  clergyman  to 
have  a  lightning  conductor  erected  at  his  house,  but  it 
so  happened  that  this  summer  was  a  very  dry  one,  and 
the  peasants,  believing  that  this  lightning  conductor 
was  the  cause  of  their  trouble,  made  so  much  noise 
about  the  matter  that  the  reverend  gentleman  had  to 
remove  it. 

The  danger  incurred  by  any  person  receiving  a  violent 
shock  from  a  conductor  drawing  electricity  from  the 
clouds  was  not  appreciated,  and  a  Russian  professor  at  St. 
Petersburg,  having  erected  an  insulated  iron  rod  leading 
into  his  house  with  the  object  of  studying  atmospheric 
electricity  thus  collected,  received  during  a  thunderstorm 
such  a  shock  that  he  was  killed  instantaneously.  This 
victim  to  scientific  research,  Professor  Richmann,  had 
omitted  to  provide  any  connection  whereby  the  electricity 
might  have  passed  harmlessly  to  earth. 

107 


DIFFERENT   KINDS   OF  LIGHTNING 

We  now  know  that  lightning  is  merely  a  sudden  dis- 
charge of  electricity  from  one  cloud  to  another,  or  from  a 
cloud  to  the  earth,  in  every  way  similar  to  the  discharge 
between  the  inner  and  outer  coatings  of  a  Ley  den  jar,  but 
on  an  immensely  grand  scale.  The  noise  of  this  great 
discharge  becomes  a  mighty  roar  as  it  echoes  through  the 
clouds. 

The  quantity  of  electricity  in  a  lightning  flash  is 
extremely  small,  but  it  is  at  a  tremendous  pressure.  Here 
we  have  electricity  leaping  a  great  distance  from  a  cloud 
to  the  earth,  across  the  intervening  air  space  measuring 
sometimes  a  mile  in  distance,  and  yet  we  should  require 
a  battery  of  one  thousand  cells  or  more  to  make  the 
current  jump  over  an  interval  of  one-thousandth  of  an 
inch  of  air  space. 

Lightning  without  thunder  is  sometimes  merely  the 
reflection  of  a  far-distant  thunderstorm,  or  at  other  times 
it  may  be  a  quiet  discharge  from  one  cloud  to  another, 
where  the  difference  of  potential  is  not  very  great. 

If  the  thunder  quickly  follows  the  lightning,  we  know 
that  the  discharge  is  taking  place  very  close  at  hand.  I 
can  remember,  when  a  youngster,  being  so  close  to  a 
lightning  discharge  that  the  flash  and  noise  seemed  simul- 
taneous. I  felt  a  sudden  contraction  of  the  muscles,  and 
I  could  plainly  smell  the  ozone  or  electrified  oxygen.  On 
this  occasion  a  building  within  a  stone's-throw  was  struck 
by  the  lightning. 

It  is  possible  to  roughly  calculate  the  distance  one  is 
from  a  thunderstorm  by  timing  the  interval  between 
seeing  the  flash  and  hearing  its  thunder.  The  light  is  seen 
practically  at  the  moment  of  discharge,  for  light  waves 

108 


A  FALSE   NOTION 

in  the  ether  would  travel  eight  times  round  and  round 
the  earth  in  one  second,  but  the  sound,  or  air  vibrations, 
will  only  travel  at  about  1,100  feet  per  second,  so  if  the 
number  of  seconds  between  the  lightning  and  thunder 
are  noted,  a  simple  calculation  will  give  the  distance  the 
sound  has  had  to  travel.  If  fifteen  seconds  elapse,  then 
the  distance  will  be  a  little  over  three  miles. 

We  can  recognise  three  different  kinds  of  lightning — 
fork  lightning,  sheet  lightning,  and  ball  lightning.  In 
fork  lightning  we  have  a  greater  disruption  than  in  sheet 
lightning,  the  latter  appears  as  a  slower  discharge,  al- 
though the  whole  time  in  which  any  electrical  discharge 
takes  place  is  a  very  small  fraction  of  a  second.  Ball 
lightning  is  rare,  and  has  the  appearance  of  balls  of 
fire  bursting  in  the  air  with  a  loud  explosion. 

It  is  very  amusing  sometimes  to  read  in  the  daily  press 
the  graphic  account  of  a  building  struck  by  lightning.  I 
recollect  one  report  reading  like  this :  "  The  lightning 
entered  the  building  by  the  chimney,  rushed  across  the 
floor,  and  making  its  way  to  the  lower  part  of  the 
house  by  the  gas-pipes,  it  forced  a  passage  through  a 
crevice,"  and  so  on ;  and  yet  all  this  took  place  within 
one  tiny  fraction  of  a  second.  The  disruptive  effects  of 
a  lightning  discharge  into  the  earth  have  sometimes  been 
so  great  as  to  give  rise  to  the  belief  that  a  material 
thunderbolt  had  been  shot  into  the  earth. 

If  we  force  a  very  fine  jet  of  water  up  into  the  air  so 
that  it  falls  in  such  fine  drops  as  to  be  little  more  than  a 
mist,  and  if  while  this  is  happening  we  electrify  a  vul- 
canite rod,  by  simply  rubbing  it  with  a  cat's  skin,  and 
bring  this  small  electrical  charge  near  to  the  fine  stream  of 

109 


SWISS   MOUNTAIN  AIR 

water  particles,  they  become  electrified,  and  uniting  to- 
gether  they  form  quite  large  drops.  This  experiment  is 
a  very  good  representation  of  the  heavy  rain  accompany- 
ing a  thunderstorm. 

One  often  feels  a  decided  heaviness  or  want  of  life  in 
the  atmosphere  immediately  before  a  thunderstorm,  but 
as  soon  as  the  storm  is  over  the  oxygen  of  the  air  seems 
to  have  gained  renewed  vigour. 

It  is  well  known  to  all  that  great  benefit  is  derived 
from  the  high  mountain  air  of  Switzerland  by  patients 
whose  breathing  apparatus  is  defective.  On  these  moun- 
tain-tops we  find  a  large  quantity  of  ozone  or  electrified 
oxygen,  and  in  addition  the  air  is  free  from  a  good  deal 
of  both  the  organic  and  inorganic  matter  to  be  found  in 
the  vicinity  of  cities,  while  the  air  being  dry  and  cold,  its 
dust  particles  are  easily  repelled  from  the  heated  surfaces 
of  the  lungs  (see  p.  137).  Some  twelve  years  ago  I  made 
the  suggestion,  through  a  medical  friend,  to  the  staff  of 
one  of  our  hospitals,  that  in  a  ward  with  patients  suffering 
from  diseased  or  weak  lungs  an  apparatus  might  be 
arranged  to  alter  very  considerably  the  conditions  of  the 
air,  and  bring  these  nearer  to  those  existing  on  the  Swiss 
and  other  mountain-tops.  I  proposed  that  the  air  should 
first  of  all  be  cleaned  by  filtering  it  through  glass-wool, 
etc.,  that  it  should  be  dried  and  then  cooled  to  a  con- 
venient temperature,  while  some  additional  oxygen  might 
be  added  if  desired,  and  then  finally  passed  through  a 
large  vulcanite  chamber,  in  which  some  high-frequency 
machines  would  be  kept  discharging,  for  the  production 
of  ozone,  and  the  air  in  this  altered  condition  might  be 

no 


THE  AURORA  BOREALIS 

led  into  the  ward  through  vulcanite  tubes  and  distributed 
at  the  patients'  bedsides. 

The  suggestion  met  with  some  approval,  and  I  was 
offered  facilities  to  carry  out  experiments,  but  not  being 
connected  either  with  the  electrical  industry  or  with 
medical  practice  I  merely  offered  the  suggestion  that  those 
specially  interested  might  make  the  experiment,  the  result 
of  which  seemed  to  me  a  foregone  conclusion.  Nothing 
was  done,  but  I  have  been  interested  to  note  of  late  that 
the  same  idea  has  been  carried  out  in  other  quarters. 

In  contrast  with  the  terrorising  lightning  we  have  the 
beautifully  peaceful  display  of  the  aurora  borealis. 
While  this  exquisite  phenomenon  is  not  of  very  frequent 
occurrence  in  our  latitude,  it  may  be  seen  nightly  in  the 
polar  regions,  but  never  at  the  equator.  This  beautifully 
luminous  effect  occurs  in  the  heavens  at  both  poles  of  the 
earth,  but  that  at  the  south  pole  is  termed  aurora 
australis.  Franklin  explained  these  phenomena  as  due  to 
discharges  of  electricity  through  rarefied  air,  such  as  we 
see  on  a  small  scale  inside  a  vacuum  tube.  The  magnet- 
ism of  the  earth  is  disturbed  in  the  neighbourhood  of 
these  displays,  and  we  have  what  are  termed  magnetic 
storms.  In  a  telephone  having  an  "  earth  return " 
instead  of  a  complete  metallic  circuit,  strange  sounds  may 
often  be  heard  in  the  stillness  of  the  night,  due  to  earth 
currents  possibly  set  up  through  the  medium  of  the  ether 
by  some  disturbances  in  the  sun.  The  whole  telegraphic 
circuits  of  this  country  are  occasionally  completely  upset 
by  these  magnetic  storms. 

Electrical  phenomena  have  long  been  known  to  exist 

in 


WONDERFUL  ELECTRIC  FISH 

in  the  animal  world — indeed,  one  of  the  earliest  electrical 
observations  was  that  of  certain  fish  being  able  to  deal 
out  startling  shocks.  This  fact  is  recorded  by  the 
greatest  of  ancient  philosophers,  Aristotle,  more  than 
three  hundred  years  before  the  Christian  era.  We  also 
have  some  interesting  details  noted  by  Pliny,  who  lived 
early  in  the  first  century  of  the  Christian  era  and  who 
lost  his  life  by  suffocation  from  the  fumes  of  the  great 
eruption  of  Mount  Vesuvius,  on  landing  to  witness  the 
great  phenomenon.  Pliny  records  the  fact  that  when 
the  torpedo,  an  electric  fish  found  in  the  Mediterranean, 
was  touched  with  a  spear,  "  it  paralyses  the  muscles  and 
arrests  the  feet,  however  swift."  Then  we  have  the 
ancient  record,  mentioned  later  in  chapter  xxiii.,  of 
a  man  having  been  cured  of  gout  by  the  shock  from 
one  of  these  torpedo  fish. 

Although  these  properties  were  known  for  suoh  a  very 
long  time  it  was  not  till  late  in  the  seventeenth  century 
that  modern  naturalists  gave  the  matter  any  serious 
attention.  It  was  only  then  that  this  shock  was  recog- 
nised as  being  of  electrical  origin. 

Our  present  knowledge  includes  some  fifty  different 
kinds  of  fishes  which  show  electrical  properties,  but  the 
best  known  are  the  Electric  Eel  (Gymnotus)  and  the 
Electric  Ray  (Torpedo  Galvani).  The  Gymnotus,  which 
measures  five  or  six  feet  in  length,  is  said  to  be  able  to 
deal  out  a  shock  sufficient  to  kill  a  man. 

Many  experiments  have  been  successfully  performed 
with  the  electricity  derived  from  these  fish,  such  as  the 
lighting  of  an  incandescent  lamp,  the  magnetising  of 
needles,  and  the  decomposition  of  water. 

XI2 


EARTHQUAKES   AND  VOLCANOES 

This  electrical  property  has  doubtless  been  bestowed 
upon  the  fishes  as  a  means  of  preying  upon  smaller  fish 
for  food,  and  probably  also  as  an  active  means  of  self- 
defence  against  greater  monsters.  There  still  remains  a 
great  deal  of  uncertainty  as  to  the  nature  of  the  pro- 
duction of  these  shocks. 

With  the  advent  of  delicate  electrical  tests  it  was 
found  that  in  our  own  bodies  there  are  continual  electri- 
cal changes  taking  place  on  a  small  scale. 

Earthquakes,  although  experienced  from  ancient  times, 
have  received  little  scientific  attention  until  quite  recently, 
and  even  now  little  is  really  known  as  to  their  origin. 
One  great  astronomer  has  asked  us  to  imagine  the  solid 
crust  of  the  earth  to  be  no  thicker  in  comparison  with  its 
molten  contents  than  an  egg-shell  is  to  its  yolk.  We  are 
then  to  suppose  an  earthquake  to  be  due  to  the  cooling 
down  and  consequent  shrinkage  of  the  molten  centre  and 
the  necessary  taking  in  of  the  outer  coating  to  adjust 
itself  to  the  new  condition,  as  an  older  brother's  suit  or 
clothes  might  be  cut  down  to  fit  a  younger  brother. 
Other  physicists  argue  that  the  earth  is  solid  throughout, 
and  that  there  is  no  fusion,  although  the  internal 
temperature  is  enormous.  The  reason  why  it  may  be  at  a 
very  high  temperature  and  yet  not  fuse  or  melt,  is  that 
the  materials  are  under  a  great  pressure,  and  if  a  body  is 
subjected  to  a  great  increase  in  pressure  it  requires  a 
very  much  higher  temperature  to  fuse  it.  This  view 
suggests  that  the  molten  effusions  from  volcanoes  are 
merely  local  and  do  not  necessarily  prove  that  the  earth's 
centre  is  molten.  If  a  body  that  would  melt  on  the 

H  113 


EARTHQUAKES   AND  VOLCANOES 

earth's  surface  at,  say,  one  thousand  degrees  be  subjected, 
in  the  bowels  of  the  earth,  to  such  a  pressure  that, 
although  it  is  there  at  a  temperature  of  two  thousand 
degrees,  it  does  not  melt,  and  if  the  pressure  be  suddenly 
removed  or  relieved  by  some  disturbance  elsewhere,  the 
heat  it  contains  will  instantly  liquefy  it.  Whatever  may 
be  the  true  causes,  for  there  will  certainly  not  be  only 
one  cause  operating,  the  great  material  disturbance  is 
bound  to  give  rise  to  an  alteration  in  electrical  conditions 
in  the  earth ;  but  my  present  purpose  in  referring  to  the 
subject  of  earthquakes  here  is  in  connection  with  the 
recording  of  such  disturbances  by  electrical  apparatus  as 
will  be  described  in  a  later  chapter. 


"4 


CHAPTER   XII 

INTERESTING  APPLICATIONS  OF 
ELECTRICITY 

What  makes  the  electric  bell  ring — How  indicators  work — An  alarm- 
clock  that  will  insist  on  its  victim  rising— Automatic  fire-alarms— 
A  room  automatically  kept  at  an  even  temperature— A  burglar 
that  knew  too  much,  and  yet  not  enough—The  block  system  on 
railways. 

IN  addition  to  the  principal  applications  of  electricity 
separately  dealt  with  in  the  various  chapters,  there  are 
manifold  other  uses  in  everyday  life  to  which  this 
willing  servant  may  be  put.     Perhaps  the  commonest  is 
the  electric  bell,  which  alone  covers  a  wide  field.     Its 
principle  is  very  simple  and  its  operation  interesting,  and 
yet  how  many  possessors  of  these  bells  have  ever  taken 
the  trouble  to  lift  off  the  outer  case  to  see  how  the  bell 
works. 

Under  normal  conditions  the  electricity  cannot  get 
from  the  battery  to  the  bell,  because  the  connecting  wire 
is  purposely  broken  at  the  "  push  "  on  the  wall,  but  when 
anyone  presses  the  button  of  the  push,  the  two  ends  of 
the  wire  are  pressed  together,  and  the  current  gets 
through,  and  rings  the  bell. 

The  current  passes  round  an  electro-magnet,  causing  it 
to  attract  a  lever  towards  it,  and  on  the  end  of  this  lever 
is  a  gong-stick,  which  thus  coming  quickly  forward  strikes 

"5 


THE   ELECTRIC   BELL 

the  bell  or  gong.  This  will,  of  course,  only  make  one 
stroke  each  time  you  send  the  current  through  by  press- 
ing the  button,  so  bells  of  this  kind  are  called  single- 
stroke  bells,  and  are  used  for  signalling  on  tramway  cars 
and  for  many  other  purposes;  but  when  you  wish  to  call 
the  attention  of  a  servant  you  prefer  to  have  something 
a  little  more  vigorous  in  its  action. 

With  the  single-stroke  bell  you  could  easily  make  a 
series  of  blows  upon  the  gong  by  repeatedly  pressing 
and  releasing  the  push  alternately,  but  this  proceeding 
would  be  rather  tiresome,  so  the  bell  is  arranged  to  do 
this  making  and  breaking  of  the  circuit  for  you.  Instead 
of  leading  the  current  directly  to  the  electro-magnet,  the 
wire  is  attached  to  a  little  pillar,  against  which  the  gong- 
stick  leans  when  at  rest,  and  the  current  must  pass  up 
this  pillar,  and  thence  through  the  gong-stick  to  the  wire 
of  the  electro-magnet.  As  soon  as  the  push  is  pressed  the 
current  gets  through  from  the  pillar  to  the  magnet,  which 
immediately  attracts  the  gong-stick  forward  against  the 
gong,  but  as  the  gong-stick  is  no  longer  touching  the 
pillar,  through  which  the  current  was  getting  over  to  the 
magnet,  the  magnetism  ceases,  and  the  gong-stick,  being 
no  longer  attracted,  falls  back  again  against  the  pillar, 
whereupon  the  current  once  more  gets  across  to  the 
magnet ;  the  gong-stick  makes  another  stroke,  falls  back 
again,  and  so  on,  continuing  to  tremble  between  the  pillar 
and  the  magnet  as  long  as  the  button  of  the  push  is  held 
in.  These  bells  are  the  ones  in  common  use,  and  are 
called  "trembler  bells." 

The  ordinary  push  consists  merely  of  two  pieces  of 
brass  spring  mounted  in  a  wooden  or  metal  case.  The 

116 


HOW  INDICATORS   WORK 

wire  from  the  battery  to  the  bell  is  cut  at  the  place  where 
the  push  is  to  be  fixed,  and  the  two  wire  ends  are  fastened 
to  the  two  brass  pieces,  which  are  normally  standing  clear 
of  each  other,  but  which  are  pushed  together  by  the  little 
"  ivory  "  button,  completing  the  circuit,  which  is  again 
broken  when  the  button  is  released. 

Before  electric  bells  came  into  use  it  was  customary  to 
fit  up,  in  the  servants'  quarters  in  a  house,  quite  an  array 
of  swinging  bells,  each  of  which  had  a  different  tone,  and 
the  maids  were  supposed  to  know  which  room  was  in- 
dicated by  the  particular  sound  of  the  bell.  We  all  have 
some  experience  of  the  inadequacy  of  such  a  system 
through  the  failure  of  a  servant  to  understand  the 
language  of  the  bells.  It  is  possible  now,  with  the  aid  of 
an  electrical  indicator  or  annunciator,  to  use  only  one  bell 
for  several  hundreds  of  rooms  in  a  large  hotel.  The  wire 
from  each  push  passes  round  a  separate  little  electro- 
magnet, and  then  to  the  one  bell,  so  that  the  current  will 
magnetise  this  special  electro-magnet  as  well  as  ring  the 
bell.  This  small  magnet  may  be  made  to  attract  a  little 
lever,  and  allow  the  flap  or  shutter  of  an  indicator  to  fall, 
leaving  the  number  of  the  room  exposed,  or  it  may  be 
made  to  set  a  small  pendulum  swinging,  on  the  bob  of 
which  is  carried  a  brightly  coloured  disc,  placed  im- 
mediately over  its  particular  number,  and  so  on.  It  may 
also  be  arranged  that  the  bell  continues  to  ring  until  the 
attendant  stops  it. 

These  continuous-ringing  bells  are  now  used  for  many 
purposes,  and  are  such  that  when  the  gong-stick  moves 
forward  under  the  first  impulse,  a  small  spring  which  was 
resting  on  the  gong-stick  falls  down  against  a  contact 

1X9 


AN  ALARM-CLOCK 

piece  and  closes  the  circuit  from  the  battery  direct  to  the 
bell,  so  that  when  the  bell  has  once  been  set  in  motion 
from  the  distant  push,  it  will  continue  ringing  until  this 
little  spring  is  lifted  off  the  contact  piece  and  again  held 
up  by  the  gong-stick.  The  value  of  such  an  arrangement 
will  be  appreciated  in  connection  with  a  fire-alarm,  as  it 
commands  attention. 

Anyone  requiring  to  rise  early  in  the  mornings,  and 
finding  the  ordinary  alarm-clock  insufficient,  may  remove 
the  gong  from  the  clock,  and  cause  the  little  gong-stick  to 
set  in  motion  one  of  these  continuous-ringing  bells,  which 
will  certainly  give  him  no  peace  till  the  unwilling  victim 
rises  and  replaces  the  contact  spring. 

Many  years  ago,  and  before  the  introduction  of  these 
continuous-ringing  bells,  I  made  up  a  reliable  alarm  in  the 
following  fashion.  Fixing  an  ordinary  trembler  bell  on 
the  outside  of  a  battery  box,  I  placed  a  brass  hinge  on 
the  top  of  the  box,  screwing  down  the  one-half  of  the 
hinge  and  leaving  the  other  free  to  be  lifted  or  let  down 
on  the  box  lid  at  pleasure.  Underneath  this  movable 
end  of  the  hinge  I  placed  a  little  metal  plate  or  contact 
piece,  fixing  one  wire  from  the  battery  to  this,  so  that  the 
current  could  only  get  to  the  hinge  when  it  was  in  con- 
tact, and  thence  by  a  wire  attached  to  the  fixed  half  of 
hinge  to  the  bell.  Having  removed  the  gong  from  an 
ordinary  cheap  alarm-clock,  I  placed  on  the  top  of  the 
clock,  and  lying  against  the  gong-stick,  a  round  piece  of 
metal  which  was  attached  by  a  string  to  the  free  end  of 
the  hinge,  normally  standing  up  away  from  the  contact 
piece.  When  the  alarm  of  the  clock  goes  off  the  gong- 
stick  kicks  the  metal  piece  off  the  top  of  the  clock,  and  in 

nS 


AUTOMATIC  FIRE-ALARMS 

falling  it  pulls  the  desk-hinge  down  on  to  the  contact 
piece  completing  the  circuit,  setting  the  electric  bell  in 
operation,  so  that  the  would-be  sleeper  must  bestir  him- 
self to  rise  and  lift  the  hinge  off  the  little  metal  plate. 
The  apparatus  is  very  simple,  and  I  used  such  an  alarm 
for  many  years,  without  finding  it  to  fail  me  once,  and 
having  given  several  young  engineers  duplicates  of  it,  I 
have  received  from  them  the  same  report. 

I  remember  one  young  engineer  who  arranged  his 
alarm-clock  so  that  as  soon  as  it  commenced  to  ring  it 
also  began  to  walk  along  the  mantelshelf,  so  that  he  had 
to  make  haste  and  check  its  suicidal  intentions.  Another 
young  man  who  desired  to  have  as  long  in  bed  as  possible 
arranged  his  clock  to  make  a  preliminary  and  somewhat 
feeble  alarm,  but  at  the  same  time  to  turn  on  the  gas- 
light under  a  small  kettle  arrangement,  and  when  the 
water  boiled  the  enclosed  steam  blew  a  whistle  placed  on 
the  tightly  fitting  lid,  thus  informing  its  master  that 
everything  was  now  in  readiness. 

We  now  have  automatic  fire-alarms,  whereby  the  ex- 
cessive heat  of  any  place  catching  fire  will  close  an  electric 
circuit  and  give  the  alarm  direct  to  the  fire  brigade.  A 
simple  arrangement  by  which  heat  may  be  made  to  close 
a  circuit  is  a  piece  of  curved  spring,  made  up  of  two  flat 
pieces  of  different  metals,  which  expand  at  different  rates, 
and  being  clamped  to  each  other  at  both  ends,  the  curved 
spring  uncurls  till  it  comes  against  a  metal  contact,  thus 
completing  an  electric  circuit,  just  as  one  does  in  pressing 
the  button  of  a  bell  push.  There  are  many  other  devices, 
but  this  one  will  serve  as  an  illustration  of  how  an  alarm 
of  fire  may  be  automatically  given. 

119 


EVEN  TEMPERATURE 

This  device,  which  is  called  a  thermostat,  may  be 
arranged  to  give  an  alarm  if  the  temperature  of  a  green- 
house rises  too  high  or  falls  too  low,  by  placing  the  free 
end  of  the  metal  curve  between  two  contact  pieces,  so 
that  if  it  either  curls  or  uncurls  a  certain  amount  it  will 
come  in  contact  with  one  or  other  of  these  metal  stops 
and  complete  the  circuit.  I  have  seen  the  temperature  of 
a  room  automatically  kept  constant  by  such  an  arrange- 
ment. Gas-stoves  were  placed  here  and  there  around  the 
room,  and  each  stove  was  under  control  of  a  thermostat, 
as  just  described.  When  the  temperature  began  to  rise, 
the  thermostat,  instead  of  causing  a  bell  to  ring,  operated 
an  electro-magnetic  device  which  lowered  the  gas,  or  if 
the  temperature  rose  sufficiently,  turned  the  gas  off 
altogether,  leaving  only  a  small  pilot  jet  burning,  similar 
to  the  by-pass  of  an  incandescent  gas  burner.  When  the 
temperature  came  down  again,  the  metallic  curve  leaving 
the  contact  piece  allowed  the  electro-magnetic  device  to 
turn  the  gas  on  again.  The  room  was  kept,  by  this 
means,  always  at  a  constant  temperature,  never  being 
more  than  half  a  degree  above  or  below  the  desired  heat. 

When  electric  heating  can  be  obtained  at  a  marketable 
price,  I  have  no  doubt  that  it  will  be  a  common  practice 
to  have  the  temperature  of  our  houses  and  offices  auto- 
matically controlled.  What  a  boon  it  will  be  to  the 
household  to  dispense  with  troublesome  fireplaces. 

If  it  is  desired  to  know  exactly  when  some  liquid 
reaches  a  definite  temperature,  it  is  an  easy  matter  to 
make  up  an  ordinary  mercury  thermometer  for  the  pur- 
pose. The  wire  from  the  battery  is  passed  through  the 
glass  bulb,  so  that  it  is  in  contact  with  the  mercury,  while 

120 


BURGLAR  THAT  KNEW  TOO  MUCH 

another  wire  enters  the  long  stem  at  the  place  where  the 
specified  temperature  is  marked  off,  so  that  as  soon  as  the 
mercury  rises  to  this  point  the  current  will  find  a  passage 
through  the  mercury  from  the  wire  in  the  bulb,  up  the 
stem,  to  the  other  wire,  and  thence  to  the  alarm-bell. 

Electricity  is  called  in  as  a  detective  to  prevent 
burglars  entering  a  house  unnoticed.  The  opening  of  a 
window  or  a  door  completes  a  circuit  and  a  bell  rings  in 
the  master's  room. 

In  America,  where  burglar -alarms  are  more  common 
than  in  this  country,  houses  are  sometimes  connected  up 
to  the  nearest  police-station,  so  that  an  alarm  may  be 
given  if  the  house  is  tampered  with  while  it  is  unoccupied. 
I  remember  hearing  of  a  burglar  who  detected  one  of 
these  wires  which  led  to  the  police-station,  and  correctly 
guessing  what  it  was,  the  burglar  took  the  precaution  to 
cut  the  line  of  communication  between  the  window  and 
the  police-office  before  attempting  to  force  an  entrance. 
No  doubt  he  would  congratulate  himself  upon  his  fore- 
sight, and  possibly  he  may  have  been  a  little  more 
deliberate  about  his  work  than  he  would  otherwise  have 
been,  for  while  he  was  still  busy  opening  the  window  he 
found  himself  in  the  clutches  of  the  law.  The  secret  of 
the  surprise  was  that  the  wire  leading  away  to  the  local 
police-office  was  carrying  a  very  weak  current,  which  kept 
a  magnetic  needle,  at  the  police-office,  deflected  to  one 
side.  If  a  window  or  door  was  opened  the  wire  was 
broken  thereby,  and  with  the  stoppage  of  the  current  the 
little  magnet  at  the  police-station  was  no  longer  deflected, 
and  on  reaching  its  normal  position  it  made  a  contact  and 
set  an  alarm-bell  going,  so  in  the  above  case  the  burglar 

121 


BLOCK   SYSTEM   ON  RAILWAYS 

sent  the  alarm  by  cutting  the  wire  before  he  attempted  to 
open  the  window. 

The  application  of  these  burglar-alarms  has  been  so 
developed  that  the  intruder  may  be  photographed  while 
tampering  with  a  safe.  A  very  clever  capture  was  made 
some  years  ago  in  America  by  an  electrical  alarm  which 
set  off  a  flash-light  and  pulled  the  trigger  of  a  camera, 
directed  to  take  a  view  of  the  front  of  the  safe.  In  this 
way  the  burglar  was  unconsciously  photographed,  and 
was  easily  recognised  by  the  police  authorities. 

There  is  an  almost  endless  variety  of  uses  to  which 
electricity  may  be  adapted  for  giving  alarms  and  signals 
of  one  kind  or  another,  but  the  one  particular  application 
which  stands  out  pre-eminently  is  that  of  signalling 
between  railway  signal-cabins.  Our  present  complicated 
railway  traffic  would  be  quite  impossible  but  for  the  aid 
of  electricity. 

Doubtless  everyone  knows  something  of  the  "block 
system  "  of  railway  working,  but  as  there  often  seems  to 
be  an  unnecessary  mystery  as  to  what  this  really  means, 
it  will  be  well  to  explain  the  principle.  The  railway  is 
divided  into  sections  or  "blocks,"  there  being  a  signal- 
cabin  at  the  entrance  and  the  exit  of  each  block,  so  that 
one  signal-cabin  controls  the  exit  from  one  block  and  the 
entrance  to  the  next. 

To  take  the  simplest  case  of  a  cabin  which  is  merely  a 
passing-place,  and  not  a  junction,  and  having  only  one  up 
and  one  down  track  to  control. 

In  addition  to  his  ordinary  telegraph  instruments  and 
signalling  bells,  by  which  the  signalman  can  communicate 
with  the  cabin  on  either  side  of  him,  he  has  a  special 

122 


BLOCK  SYSTEM   ON  RAILWAYS 

needle  instrument  for  indicating  whether  there  is  a  train 
in  his  section  or  not.  It  will  be  remembered  that  in  a 
needle  telegraph  the  little  magnet,  being  pivoted  at  its 
centre,  remains  vertical  or  upright  when  at  rest,  but  if  a 
current  is  sent  through  the  coil  in  one  direction  the 
magnet  will  be  deflected  to  the  right,  while  a  current  sent 
in  at  the  opposite  end  of  coil  will  deflect  the  needle  to  the 
left,  so  that  the  needle  has  three  distinct  positions — up- 
right, slanting  to  the  right,  and  slanting  to  the  left — any 
of  which  it  may  be  made  to  take  up  at  will  and  remain 
there  as  long  as  the  current  is  left  on.  The  dial  of  the 
indicating  telegraph  is  marked  off  so  that  when  the  needle 
is  standing  upright  it  points  to  the  words  "  line  blocked," 
which  signifies  that  the  semaphore  signals  are  set  at 
danger,  but  that  there  is  no  train  on  the  section  between 
the  cabins.  When  the  needle  is  deflected  to  the  right  it 
points  to  the  words  "line  clear,"  which  informs  the  signal- 
man that  the  section  has  been  prepared  to  receive  a  train, 
the  outdoor  semaphore  signals  having  been  lowered. 
Slanting  to  the  left  the  needle  points  to  the  words  "  train 
on  line,"  meaning  that  a  train  is  actually  passing  between 
the  cabins.  This  special  telegraph  instrument  we  will 
call  the  "block"  instrument. 

The  working  of  these  signals  may  be  simply  illustrated 
by  supposing  that  we  are  in  the  central  cabin,  No.  2, 
having  No.  1  to  our  right  and  No.  3  to  our  left.  A  train 
is  on  its  way  from  No.  1  to  No.  2,  so  No.  2  telegraphs 
to  No.  3  asking  him,  in  code,  if  his  line  is  clear ;  this  he 
does  on  his  ordinary  telegraph  apparatus.  If  the  train 
may  proceed,  No.  3  answers,  in  code,  that  the  line  is 
clear,  and  he  also  puts  his  block  instrument  to  "line  clear," 

123 


BLOCK   SYSTEM   ON   RAILWAYS 

which  at  the  same  time  makes  No.  2's  block  instrument 
point  to  the  same  words.  The  needles  remain  in  this 
position,  so  that  No.  3  cannot  forget  that  he  has  given 
permission  for  a  train  to  come  on,  and  No.  2,  looking  at 
his  indicator,  has  confidence  in  sending  on  the  train,  and 
he  can,  therefore,  set  his  outdoor  signals  to  the  "  clear " 
position,  the  semaphore  signal  being  analogous  to  a 
policeman  who  holds  out  his  arm  to  stop  the  traffic,  and 
drops  it  to  his  side  to  let  the  driver  know  he  may  pass. 
The  engine-driver  must  not  dare  to  go  past  the  policeman- 
signal  when  the  arm  is  up. 

When  the  train  is  entering  No.  3  section  from  No.  2, 
the  latter  signalman  must  telegraph  to  No.  3,  saying, 
"  train  entering  section,""  and  No.  3  must  acknowledge  it, 
and  change  the  block  instrument  in  his  own  and  No.  2"*s 
cabin  to  "train  on  line,"  where  it  will  remain  as  a 
constant  reminder  to  both  men  that  there  is  a  train  in 
their  section. 

When  the  train  has  passed  No.  3  and  gone  into  the 
fourth  section,  No.  3  advises  No.  2  by  telegraph,  "  train 
out  of  section,""  and  also  moves  their  block  instruments  to 
"line  blocked.""  There  are  many  varieties  of  block- 
signalling  instruments,  but  the  one  just  described  will 
serve  to  illustrate  the  principle. 

I  have  often  found  people  giving  an  entirely  wrong 
meaning  to  the  block  system,  believing  that  it  is  im- 
possible for  a  signalman  to  allow  a  train  to  pass  when  the 
line  is  not  clear,  because  of  some  connection  between  the 
outdoor  signals,  or  the  train  itself,  and  the  telegraph 
apparatus,  but  in  the  ordinary  block  system  in  general 
use  there  is  no  such  connection.  The  conditions  of 

124 


BLOCK  SYSTEM   ON  RAILWAYS 

working  are  just  such  as  have  been  briefly  indicated  here, 
in  which  the  block  telegraph  may  be  regarded  merely  as 
a  safeguard  in  making  the  instructions  from  one  signal- 
cabin  to  the  next  quite  clear  and  "permanent"  till  the 
duties  have  been  performed,  but  it  is  a  possibility  for  the 
man  at  No.  3  to  signal  "  train  out  of  section  "  to  No.  2 
before  the  train  has  really  passed,  and  in  the  same  way 
it  is  possible,  though,  fortunately,  not  very  probable,  that 
No.  2  may  send  on  a  train  without  getting  permission  to 
do  so. 

The  block  system  does  not  relieve  the  signalman  of  his 
responsibilities  and  reduce  him  to  a  mere  automaton,  as 
some  people  are  inclined  to  think,  but  its  great  advantage 
is  that  the  needle  keeps  pointing  to  the  instructions  until 
they  have  been  made  use  of. 

There  is  a  method,  called  the  "  lock  and  block  system," 
in  which  the  outdoor  mechanical  signals  are  really  con- 
nected to  the  circuit  controlling  the  block  telegraph,  so 
that  when  "  line  clear  "  is  signalled  the  telegraph  is  locked 
in  that  position  until  the  train,  when  passing  the  outdoor 
signal,  depresses  a  lever,  thus  releasing  the  semaphore 
arm,  which  in  turn  operates  the  block  telegraph.  This 
system,  however,  is  not  in  general  use.  If  the  signalman's 
duties  were  merely  routine  work,  this  lock  and  block 
system  might  come  into  more  general  use,  but  as  his 
duties  are  such  that  he  cannot  be  merely  an  unthinking 
automaton,  he  is  provided  with  a  key  by  which  he  can 
disconnect  this  lock  and  block  arrangement  and  act  as 
necessity  requires,  and  in  this  there  may  be  possible 
confusion. 

Apart  altogether  from  these  block  systems,  there  is  an 
125 


BLOCK   SYSTEM   ON  RAILWAYS 

interlocking,  at  junctions,  between  the  semaphore  signal 
and  the  railway  points,  so  that  the  signalman  cannot 
lower  his  signal  until  he  has  moved  the  points,  and  he 
cannot  put  the  points  back  again  until  he  has  put  the 
signal  to  danger ;  but  this  is  merely  a  mechanical  arrange- 
ment. 

The  signalman  usually  supplies  the  energy  required  to 
move  the  outdoor  signals  and  points,  these  being  connected 
with  pulling  wires  and  moving  levers,  but  there  are  now 
some  places  equipped  with  small  electro-motors  to  supply 
the  necessary  movements. 


126 


CHAPTER  XIII 

FURTHER  APPLICATIONS   OF 
ELECTRICITY 

An  immense  lift  for  an  electro-magnet— Electricity  gives  gas  a  helping 
hand— Electricity  on  board  a  man-of-war — A  note  on  Guy  Fawkes 
—Blasting  on  a  grand  scale— Torpedoes— Recording  the  velocity 
of  projectiles— Electric  clocks— An  electric  log— Paradoxes  of  elec- 
tricity—Electrocution—Quick news  of  the  battle  of  Tel-el-Kebir— 
The  untrustworthy  telephone— Can  fogs  be  dispelled  ? 

IN  steel  and  iron  works  large  electro -magnets  have 
recently  been  brought  into  use  for  lifting  heavy  metal 
plates,  etc.  Instead  of  fixing  a  chain  and  hooks 
around  the  plate,  the  crane  merely  carries  a  large  electro- 
magnet at  the  end  of  its  wire  rope  or  chain,  and  this 
magnet  attracts  the  plate  and  holds  on  to  it  as  long  as 
the  current  is  kept  switched  on  to  the  magnet.  In  the 
accompanying  illustration  a  large  magnet  is  shown  lifting 
a  heavy  casting  weighing  about  three  tons,  and  on  the 
same  page  may  be  seen  an  ordinary  kitchen  poker  lifting 
scissors  and  keys,  which  serves  to  show  the  principle. 

Electricity  and  gas  are  strong  rivals  as  illuminants,  but 
we  sometimes  find  electricity  giving  gas  a  helping  hand. 
When  a  large  chandelier  is  out  of  easy  reach  and  cannot 
be  conveniently  lighted  by  a  taper,  it  is  only  necessary  to 
arrange  a  short  gap  for  an  electric  current  to  spark  across, 
and  to  arrange  that  when  the  gas  is  turned  on  the  electric 

127 


ELECTRICITY  ON  A  MAN-OF-WAR 

current  is  also  momentarily  switched  on,  and  the  gas  thus 
ignited  by  the  spark.  This  simple  but  useful  application 
dates  back  to  1839,  at  which  time  few  practical  applica- 
tions of  electricity  had  been  made.  Indeed,  I  was  rather 
surprised  the  other  day  on  picking  up  a  science  book, 
published  in  London  in  1840,  to  find  the  following  state- 
ment :  "  It  must  be  allowed,  that  the  case  has  not  been 
the  same  with  electricity  as  with  magnetism.  The  latter, 
by  the  invention  of  the  magnetic  needle,  has  served  to 
render  navigation  more  secure,  and  to  discover  the  new 
world,  a  source  of  new  riches,  new  wants,  and  of  new  evils 
to  the  old  one.  But  electricity  has  not  yet  produced 
any  thing  of  so  much  importance,  to  mankind,  and  to  the 
arts,  if  we  except  the  analogy  now  proved  between  the 
electric  fire  and  lightning:  an  analogy  which  has  given 
rise  to  a  pretty  sure  preservative  from  the  effects  of  that 
dreadful  meteor;  for  in  regard  to  the  cures  effected  by 
electricity,  it  must  be  acknowledged  that  they  are  either 
rare,  or  not  well  ascertained." 

What  benefits  we  have  reaped  from  the  applications  of 
electricity  during  the  years  that  have  passed  since  the 
above  lines  were  first  penned ! 

A  steamer  equipped  with  a  powerful  electric  search- 
light is  at  a  great  advantage  in  many  ways.  We  may 
take  as  an  illustration  an  incident  which  happened  some 
years  ago  on  a  British  man-of-war,  and  may  have  been 
repeated  often  since  the  occasion  referred  to.  The  ship 
was  steaming  along  on  a  very  dark  night  when  the  cry 
was  raised  of  "Man  overboard.11  It  is  not  difficult  to 
realise  the  horror  of  those  on  board  when  thinking  of 
the  speed  the  vessel  was  making  and  the  dense  blackness 

128 


A  NOTE   ON   GUY  FAWKES 

of  the  night.  How  many  sailors  are  lost  every  year  even 
from  slow-going  vessels  because  it  is  impossible  to  find 
the  whereabouts  of  the  lost  man  in  the  darkness !  In  the 
case  of  this  British  warship,  two  of  her  officers  happened 
to  see  the  sailor  fall  off  the  rigging,  and  both  immediately 
dived  into  the  water  to  the  poor  man's  rescue.  The  great 
searchlight  at  once  scanned  the  water,  and  soon  revealed 
the  three  men  clinging  to  a  lifebuoy.  The  searchlight 
kept  them  in  view  while  the  steamer  slowed  down  and 
swung  round,  so  that  the  lifeboat  was  able  to  go  straight 
to  the  men  in  the  water,  and  it  was  reported  that  within 
six  minutes  the  men  were  saved,  the  lifeboat  hoisted,  and 
the  great  ship  once  more  on  her  way. 

In  time  of  war  electricity  now  plays  a  very  prominent 
part,  not  only  as  a  carrier  of  intelligence,  but  as  a  prompt 
and  sure  assistant  in  the  firing  of  guns  and  the  exploding 
of  distant  mines.  It  is  even  made  possible  for  the  captain 
of  a  large  warship  to  fire  a  whole  broadside  simultaneously, 
the  commanding  officer  being  able  to  see  from  instruments 
in  his  conning-tower  when  all  the  guns  are  set  and 
ready. 

Not  only  may  submarine  mines  be  exploded  electrically 
by  making  a  small  platinum  wire  red  hot,  but  much  the 
same  may  be  done  on  land.  During  the  Russo-Japanese 
War  we  saw  what  a  terrible  disaster  may  be  brought 
about  by  the  enemy  undermining  a  whole  roadway,  and 
then  by  electrical  means  firing  the  mine  from  any  distance 
at  the  moment  their  opponents  have  reached  the  prepared 
spot,  and  in  this  heartless  fashion  practically  annihilating 
a  whole  regiment. 

It  is  very  well  that  Guy  Fawkes  was  born  too  early  to 
i  129 


BLASTING   ON  A  GRAND   SCALE 

obtain  assistance  from  electricity  in  the  firing  of  explo- 
sives, or  he  and  his  friends  might  have  succeeded  in 
evading  suspicion  in  connection  with  the  vault  they  rented 
under  the  House  of  Lords.  Having  once  secreted  the 
thirty-six  barrels  of  gunpowder  unnoticed,  they  could 
have  left  the  store  closed,  knowing  that  they  would  be 
able  to  fire  the  explosives  from  their  adjoining  house  at 
the  moment  when  Parliament  had  assembled.  Even  the 
anonymous  and  vague  letter  of  warning  might  have 
failed,  for  it  was  only  when  the  Lord  Chamberlain  saw 
"  this  very  tall  and  desperate  fellow "  in  charge  of  the 
vaults  that  his  suspicions  were  really  aroused. 

Electricity  has  made  it  possible  to  fire  very  large  blasts 
for  clearing  away  rocks,  etc.  To  form  an  adequate  con- 
ception of  this  application  of  electricity,  it  is  worth  while 
picturing  the  great  blasting  operations  which  took  place 
some  twenty  years  ago  in  America,  in  the  destruction  of 
Flood  Rock,  in  the  East  River,  near  New  York.  About 
nine  acres  of  solid  rock  were  undermined  and  honey- 
combed, and  over  thirteen  hundred  holes  were  drilled,  in 
which  were  placed  the  explosives.  Each  dynamite  cart- 
ridge was  provided  with  an  electric  fuse,  and  a  wire  was 
run  out  and  connected  to  a  number  of  fuses  in  one  parti- 
cular section,  and  then  back  to  the  controlling  station 
again,  each  section  being  arranged  in  this  way.  Then 
the  ends  of  the  leading-out  wires  were  all  brought  to- 
gether and  placed  in  a  vessel  of  mercury,  while  the  ends 
of  all  the  leading-in  wires  were  placed  in  a  second  vessel 
of  mercury.  It  only  remained  now  to  take  a  powerful 
battery,  and  place  one  wire  in  the  mercury  at  the  leading- 
out  ends  and  the  other  wire  in  the  mercury  at  the  leading- 

130 


TORPEDOES 

in  ends,  thus  completing  the  circuit,  and  allowing  the 
current  to  fly  out  to  all  these  fuses  in  the  dynamite  cart- 
ridges, causing  the  simultaneous  explosion  of  over  300,000 
pounds  weight  of  dynamite,  etc.,  and  blowing  up  many 
thousands  of  tons  of  solid  rock. 

The  ordinary  torpedo  of  naval  warfare  is  purely 
mechanical,  and  has  no  connection  with  electricity,  but  is 
propelled  by  compressed  air  furnishing  the  necessary 
power  to  its  engines.  For  harbour  defence  work  electri- 
city has  been  called  into  the  service  of  the  torpedo,  as  in 
the  Sims- Edison  torpedo,  in  which  the  power  is  conveyed 
by  means  of  electricity  from  a  dynamo  on  land  or  on 
board  a  ship,  but  the  disadvantage  is  a  long  trailing 
cable,  connecting  the  dynamo  with  small  electro-motors 
in  the  torpedo. 

It  has  been  suggested  to  control  the  steering  gear  of 
torpedoes  by  means  of  ether  waves,  as  used  in  wireless 
telegraphy.  This  has  been  found  quite  possible,  and 
several  patents  have  been  taken  out  in  this  connection. 
Be  it  noted  that  the  ether  waves  do  not  convey  the  pro- 
pelling power,  as  some  writers  have  set  forth,  but  merely 
operate  upon  a  "coherer,"  as  in  a  wireless  telegraph 
receiver,  switching  off  and  on  the  local  power  to  the  differ- 
ential gear  controlling  the  steering  apparatus. 

Electricity  enables  us  to  measure  the  speed  at  which 
projectiles  are  flying.  An  electrical  contact  may  be 
placed  at  any  point  in  the  path  of  a  projectile,  so  that 
the  exact  fraction  of  a  second  at  which  it  passed  this  point 
may  be  recorded  on  a  chronograph,  as  will  be  described  in 
connection  with  "Electricity  in  the  Observatory."  A 
'second  contact-maker  placed  at  any  given  distance  will 

131 


ELECTRIC   CLOCKS 

note  the  time  at  which  the  projectile  passes  it,  and  in  this 
way  the  time  taken  to  travel  from  the  one  point  to  the 
other  has  been  recorded.  It  is  even  possible  to  place  two 
contacts  at  different  parts  in  the  bore  of  a  gun,  and  thus 
find  the  velocity  of  the  projectile  before  it  leaves  the 
mouth  of  the  projector,  and  the  time  noted  may  be  cor- 
rectly measured  to  the  T ^Vu^h  part  of  a  second. 

Electricity  now  aids  in  the  measuring  of  time  for 
everyday  requirements,  either  in  controlling  the  clock 
or  in  propelling  it.  In  the  former  the  swing  of  the 
pendulum  is  merely  hastened  or  retarded  by  an  electric 
impulse  sent  out  every  second  by  a  standard  clock  to  a 
large  coil  of  wire,  inside  which  a  magnet  swings,  attached 
to  the  "  bob  "  of  the  pendulum. 

In  the  latest  form  of  electrically  driven  clocks  there 
is  merely  a  dial  with  an  electro-magnet  and  lever  opera- 
ting a  toothed  or  ratchet  wheel,  moving  forward  the 
minute  hand  of  the  clock  one  step  at  each  half  minute, 
the  hour  hand  being  geared  to  this  in  the  ordinary  way. 
An  electric  impulse  is  received  by  the  electro-magnet  at 
every  half  minute  through  a  large  standard  clock  which 
closes  the  circuit  once  every  thirty  seconds. 

It  does  seem  rather  ridiculous  that  we  shoujd  be  con- 
tent to  have  in  every  city  a  multitude  of  little  pieces  of 
somewhat  complicated  mechanism,  each  little  item  trying 
to  do  exactly  the  same  as  its  neighbour,  and  each  re- 
quiring individual  attention,  supplying  it  with  a  store 
of  energy  once  daily  or  weekly,  while  some  skill  is  re- 
quired to  specially  regulate  each  individual  clock.  Why  not 
have  one  standard  clock  for  every  city,  checked  by  the 
local  or  nearest  observatory,  and  closing  at  the  end  of 

132 


AN  ELECTRIC  LOG 

each  half  minute  an  electric  contact,  allowing  current  to 
pass  out  to  all  the  dials  and  thus  move  their  respective 
hands  forward  one  half  minute. 

It  is  even  possible  to  have  such  dials  fitted  with  a 
wireless  "  coherer "  to  catch  ether  waves,  and  switch  off 
and  on  a  local  battery  in  the  clock  to  operate  its  hands. 
I  fear  that  any  public  clocks  of  this  kind  might  pick  up 
wireless  telegraph  messages  and  become  rather  eccentric 
in  their  behaviour.  One  could  imagine  a  clock  coming 
within  the  influence  of  waves  intended  for  a  wireless 
station,  and  if  the  message  was  a  lengthy  one,  the  public 
on  consulting  the  wireless  clock  would  think  that  time 
was  literally  flying.  Here,  again,  these  ether  waves  do 
not  drive  the  clock,  but  merely  control  the  driving  power 
in  the  clock. 

The  uses  to  which  the  transmission  of  power  by 
electricity  may  be  put  are  legion.  For  instance,  one 
may  place  the  various  parts  of  a  large  organ  in  any 
desired  positions  in  a  large  hall  or  cathedral,  keeping  the 
echo  organ  at  quite  a  distance  from  the  other  parts, 
while  the  keyboard  may  be  put  in  any  convenient  place. 
In  depressing  the  organ  keys,  the  organist  merely  makes 
electrical  contacts,  thus  allowing  current  to  pass  to  the 
different  electro-magnets  opening  the  pipes. 

Electric  pianos  have  also  been  constructed,  so  that  a 
pianist  might  perform  from  any  distance,  but  this  does 
not  lend  itself  to  any  very  practical  use,  more  especially 
as  we  now  have  so  many  clever  automatic  pianolas,  etc. 

On  board  ship  the  log  may  be  taken  by  electricity. 
The  electric  log  consists  of  a  "  fly "  or  screw  which  is 
trailed  after  the  ship,  and  revolves  in  proportion  to  the 

'33 


PARADOXES   OF  ELECTRICITY 

speed  at  which  the  ship  is  travelling.  This  revolving 
screw  is  arranged  to  make  an  electric  contact,  thus  working 
an  indicator,  or  making  a  pen  move  over  a  revolving  drum 
after  the  fashion  of  the  wind  velocity  instruments  to  be  de- 
scribed in  the  chapter  on  "  Electricity  in  the  Observatory."" 
A  rather  curious  application  of  electricity  is  to  be 
found  in  the  hairdresser's  establishment.  He  makes  use 
of  electricity  either  to  destroy  the  roots  of  superfluous 
hairs,  or  to  stimulate  the  growth  of  the  hair.  This  may 
seem  rather  paradoxical,  but  what  works  in  greater  con- 
trasts than  electricity  ?  It  sounds  an  alarm  at  the  outburst 
of  fire,  and  thus  protects  from  danger  both  lives  and 
property,  but  it  also  most  stealthily  fires  the  submarine 
mine  and  sends  a  whole  crew  to  the  bottom  of  the  ocean, 
sinking  along  with  them  a  man-of-war  costing,  per- 
haps, a  million  golden  sovereigns.  Again,  in  the  hands 
of  the  physician  it  will  cure  and  save  life,  but  in  the 
hands  of  tlie  executioner  it  will  injure  and  kill.  This 
last-mentioned  application  of  electricity,  which  is  now 
the  method  of  executing  the  death  penalty  in  the  United 
States,  has  doubtless  been  somewhat  unsatisfactory,  owing 
to  a  restriction  that  the  current  used  must  not  distort 
or  disfigure  the  body  of  the  criminal.  In  some  cases 
death  has  not  been  instantaneous,  whereas,  but  for  the 
restriction  just  mentioned,  it  could  easily  have  been  made 
absolutely  sure  that  death  would  ensue  before  the  nerves 
could  communicate  any  sense  of  pain  to  the  brain.  Given 
a  free  hand  and  electrocution  would  be  the  most 
humane  method.  What  if  the  lifeless  body  were  dis- 
figured or  even  totally  cremated  by  the  electric  current ! 
Surely  this  would  be  infinitely  better  than  our  present 

134 


TELEGRAPHING  PHOTOGRAPHS 

barbarous  method  of  carrying  out  the  death  penalty  in 
these  islands! 

Let  us  pass  from  this  depressing  subject  to  that  of 
warfare.  War  must  appear  to  all  thinking  people  as  a 
barbarous  relic  of  the  past,  entailing  the  destruction  of 
thousands  of  innocent  lives  over  some  national  quarrel, 
based,  it  may  be,  on  some  misunderstanding ;  but  even  in 
warfare  we  may  find  electricity  performing  many  peaceful 
as  well  as  destructive  acts. 

All  modern  armies  have  their  own  telegraph  experts, 
and  it  was  found  possible  during  the  British  operations 
in  Egypt  in  1882  to  keep  the  advance  guard,  not  only  in 
constant  communication  with  the  headquarters,  but  with 
Great  Britain  itself.  By  this  means  the  news  of  the  victory 
of  Tel-el-Kebir  was  telegraphed  from  the  battlefield  to 
the  late  Queen  Victoria,  and  her  congratulations  were 
received  in  reply  within  three-quarters  of  an  hour  after 
the  victory  was  won. 

If  any  one  had  spoken  of  sending  photographs  by  tele- 
graph a  few  years  ago,  we  should  have  thought  the 
suggestion  was  made  merely  as  a  jest.  It  is  impossible 
to  send  the  actual  photographs  along  the  wire,  but  re- 
productions are  made  at  the  distant  place.  The  photo- 
graph at  the  sending  end  is  transparent  and  controls  a 
beam  of  light  passing  through  it.  The  varying  light 
affects  a  selenium  cell,  causing  it  to  alter  its  resistance 
to  an  electric  current  passing  through  it.  The  resulting 
current  passes  out  to  the  distant  station,  where  it  con- 
trols another  beam  or  pencil  of  light,  which  builds  up 
a  reproduction  of  the  transmitting  photograph.  Full 
details  are  given  in  The  Romance  of  Modern  Photography. 

'35 


UNTRUSTWORTHY  TELEPHONE 

Before  closing  this  chapter,  which  does  not  attempt  to 
include  all  the  applications  of  electricity,  I  should  like 
to  mention  two  more.  I  have  repeatedly  read  that  the 
microphone,  which  is  simply  a  sensitive  telephone,  is  used 
by  medical  men  as  a  delicate  stethoscope,  but  from  ex- 
periments I  made  in  this  connection  many  years  ago  on 
behalf  of  some  medical  men,  I  found  that  the  sounds  set 
up  by  every  slight  variation  of  the  current  in  the  micro- 
phone were  a  great  disadvantage.  Even  a  very  clever 
mechanical  stethoscope  made  on  the  Continent,  while 
magnifying  the  sounds  greatly,  so  that  one  can  hear  a 
friend's  heart  beat  like  a  sledge-hammer,  even  through 
his  overcoat,  has  not,  I  believe,  proved  a  practical  success 
for  distinguishing  the  different  internal  sounds.  It  might 
serve  as  a  quick  means  of  discovering  if  there  was  any 
heart-beat  in  the  case  of  an  apparent  death.  I  have  seen 
it  used  for  this  purpose,  but  from  inquiries  I  do  not  find 
that  it  has  come  into  any  general  use.  This  mechanical 
stethoscope  is  much  simpler  than  an  electric  one  would 
be,  so  that  there  does  not  seem  a  reliable  foundation  for 
these  repeated  reports  regarding  them. 

I  think  the  case  is  very  similar  to  one  I  had  knowledge 
of  some  years  ago.  I  had  made  up  an  electrical  device, 
by  which  the  cries  of  an  infant  in  its  cot  would  auto- 
matically ring  an  electric  bell  in  the  servants1  quarters. 
I  found  it  possible,  but  not  a  practical  apparatus  to  be 
left  in  the  hands  of  domestic  servants,  and  so  I  altered  it 
to  a  loud-speaking  telephone,  by  which  the  cries  could  be 
heard  at  any  distance.  Having  written  a  description  of 
this  suggested  automatic  alarm  for  one  of  the  electrical 
journals.  I  was  rather  surprised  when  two  years  later  a 

136 


CAN  FOGS   BE   DISPELLED? 

friend  drew  my  attention  to  a  description  of  it  in  a 
popular  magazine,  wherein  it  was  stated  that  the 
apparatus  was  in  everyday  use  in  America,  which  I 
knew  was  not  the  case.  Possibly  the  article  was  copied 
in  some  American  journal,  from  which  it  found  its  way 
again  in  a  slightly  altered  form  to  a  monthly  magazine 
on  this  side,  and  on  its  way  the  misunderstanding  had 
arisen. 

Another  application  of  electricity  has  reference  to  the 
deposition  of  smoke  and  fog.  It  has  long  been  well 
known  that  a  hot  body  will  repel  dust  particles  in  the  air 
while  a  cold  body  will  attract  them.  This  is  easily 
proved  by  a  very  simple  experiment.  If  a  globe  of  hot 
water  and  a  globe  of  cold  water  be  placed  under  a  glass 
cover  and  some  magnesium  ribbon  be  burned  inside  the 
cover,  it  will  be  seen  that  the  dust  particles  all  gather  on 
the  cold  globe,  while  the  heated  one  remains  dust-free. 
It  was  found  that  if  a  platinum  wire  were  heated  by  an 
electric  current  in  the  smoky  air  of  a  glass  jar,  the  air 
became  clear  and  the  dust  was  quickly  deposited  on  the 
inner  surface  of  the  jar.  It  was  proved  later  that  the 
same  effect  could  be  produced  by  electrifying  the  air,  for 
a  high-potential  electrical  discharge  inside  the  jar  soon 
cleared  the  air  of  dust.  This  has  found  a  practical 
application  in  depositing  the  harmful  fumes  in  lead  works. 

As  a  dust-laden  atmosphere  is  necessary  for  the  forma- 
tion of  fogs,  mists,  clouds,  or  rain,  it  is  evident  that  by 
electrifying  the  air  and  depositing  the  dust  we  should 
clear  the  atmosphere  of  fog.  To  do  so  in  a  wholesale 
fashion  would  doubtless  cost  a  ransom,  but  Sir  Oliver 
Lodge  suggests  that  this  might  be  done  at  important 


CAN  FOGS   BE  DISPELLED? 

centres  where  the  fog  is  most  dangerous.  While  the 
Principal  of  Birmingham  University  suggests  this  method, 
he  does  not  believe  it  to  be  the  right  remedy  any  more 
than  free  meals  and  free  doles  are  a  sound  remedy  for  the 
problem  of  poverty,  but  in  the  absence  of  a  better 
remedy  it  is  worth  a  trial. 

Electricity  has  been  applied  in  agriculture  also.  The 
origin  of  the  latest  plan  is  of  interest.  Professor  Lem- 
storm,  of  Sweden,  was  making  some  electrical  experi- 
ments to  imitate  the  Aurora  Borealis.  He  made  these 
in  his  greenhouse,  and  he  observed  that  the  plants  in  the 
neighbourhood  of  his  apparatus  seemed  to  thrive  excep- 
tionally well.  This  led  him  to  try  the  effect  of  similar 
high-tension  discharges  upon  fields  of  growing  grain. 
The  necessary  current  is  now  obtained  by  means  of  a 
dynamo  and  induction  coil,  and  the  discharge  is  made 
from  a  network  of  wires  erected  over  the  field.  The 
appearance  is  that  of  several  rows  of  telegraph  poles, 
there  being  about  one  hundred  yards  between  each  row. 
The  wires  on  these  carry  the  main  charge,  while  finer 
wires  connect  the  parallel  wires  together  every  twelve 
yards.  Wheat  grown  under  electric  discharges  has 
yielded  an  increase  of  thirty  and  forty  per  cent  more 
than  that  from  part  of  the  same  field  unelectrified.  The 
wires  may  be  placed  about  fifteen  feet  above  the  ground, 
and  the  poles  are  so  far  apart  that  there  is  no  difficulty 
in  carrying  on  the  ordinary  work  of  the  field.  The  cost 
of  supplying  the  necessary  current,  apart  from  the  first 
cost  of  the  installation,  is  very  small.  It  practically 
means  the  cost  of  running  a  small  oil-engine  or  other 
motor  for  driving  the  dynamo. 


CHAPTER  XIV 
ELECTRICITY  AND   SPEECH 

What  speech  is  really — How  electricity  produces  sound — Useful 
invention  by  a  clergyman — How  telephone  exchanges  are 
worked — Some  amusing  ideas — Central-battery  system — Clever 
signalling  apparatus — The  "howler'' — Who  keeps  a  note  of 
subscriber's  calls  ? 

SOME  people  are  content  to  go  through  life  without 
ever  stopping  to  think  how  it  is  that  we  can  produce 
speech.  The  whole  subject  of  sound,  which  branch 
of  science  is  called  acoustics,  is  a  most  interesting  one  to 
every  one  who  cares  to  study  it. 

It  is  known  to  all  that  when  a  body  produces  or  emits  a 
sound  such  a  body  must  be  in  vibration  in  order  to  dis- 
turb the  surrounding  air  and  set  up  similar  vibrations  in 
it,  which  in  turn  strike  upon  the  drums  of  our  ears  and 
cause  certain  sensations  to  be  conveyed  by  our  auditory 
nerves  to  the  sensorium.  The  setting  up  of  such  air 
vibrations  is  very  apparent  in  the  beating  of  the  big 
drum,  the  clapping  of  cymbals,  the  striking  of  a  piano 
key,  the  bowing  of  a  violin  string,  and  so  forth.  Again, 
we  have  the  vibrating  reeds  in  many  wind  instruments, 
and  in  others,  such  as  flutes  and  trumpets,  we  have  a 
column  of  air  in  vibration. 

The  air  being  matter  in  a  gaseous  state,  is  made  up  of 
tiny  little  particles  or  molecules,  and  it  is  each  of  these 

139 


ELECTRICITY  REPRODUCES   SOUND 

molecules  of  gas,  far  beyond  even  microscopical  vision, 
which  vibrates  to  and  fro.  As  each  little  molecule  has,  as 
it  were,  to  nudge  his  neighbour  into  motion,  it  is  natural 
that  the  energy  thus  transmitted  soon  dissipates  itself,  so 
that  the  molecules  at  a  distance  do  not  receive  any  appre- 
ciable disturbance  unless  the  sounding  body  is  in  very 
violent  vibration,  and  even  then  the  sound  soon  dies  away 
in  the  air  as  the  distance  increases.  As  a  matter  of  fact, 
the  air  does  not  conduct  vibrations  (sound)  nearly  so  well 
as  a  liquid,  which  has  much  greater  elasticity ;  and  on  the 
same  principle  a  solid  is  a  better  conductor  of  sound 
than  a  liquid.  The  string  telephone,  which  although 
merely  a  child's  plaything  is  yet  of  much  scientific 
interest,  is  a  good  illustration  of  a  solid  body  (the 
string)  conducting  sound  better  than  the  surrounding 
air. 

Early  in  last  century  a  London  professor  gave  a  very 
good  illustration  of  this  property  of  solids  to  an  audience 
in  the  Polytechnic  Institution  in  London.  A  band  of 
musicians  were  placed  in  a  room  in  the  basement  of  the 
building,  and  from  this  room  long  solid  metal  rods  were 
carried  right  up  through  the  principal  hall  and  into  a 
room  on  the  upper  floor,  where  they  were  attached  to 
ordinary  sounding  boards,  a  number  of  rods  and  boards 
being  used  simply  to  increase  the  effect.  When  the 
musicians  played  in  the  basement  the  audience  in  the 
upper  room  heard  the  music  as  clearly  as  if  it  were  being 
performed  there,  but  in  the  principal  hall,  through  which 
the  rods  passed,  no  sound  was  heard. 

This  illustration  enables  one  to  realise  what  a  good 
conductor  of  sound  a  metal  rod  is  ;  but  it  is  quite  evident 

140 


ELECTRICITY   REPRODUCES    SOUND 

that  these  vibrations  when  handed  on  from  one  to  another 
of  myriads  of  molecules  will  soon  dissipate  as  the  length 
of  the  rod  is  greatly  increased ;  and  in  addition  there  will 
be  a  certain  amount  of  damping  or  lessening  of  these 
vibrations  at  each  point  where  the  rod  is  supported.  It 
was  really  in  connection  with  this  set  of  rods  and  boards 
just  described  that  the  word  "  telephone "  was  first 
invented,  in  order  to  express  the  idea  of  carrying  sound 
(Greek,  phone)  to  a  distance  (Greek,  tele) 

It  is  quite  possible  to  have  a  speaking  telephone  of  this 
nature  over  a  limited  distance.  In  such  a  telephone  we 
have  a  metal  disc  against  which  one  person  speaks,  while 
the  distant  listener  stands  opposite  a  similar  disc,  the  two 
metal  plates  or  discs  being  connected  by  a  tightly 
stretched  wire.  It  is  marvellous  that  a  flat  metal  disc, 
receiving  vibrations  conveyed  by  the  wire  from  the 
distant  disc,  can  set  up  exactly  the  same  vibrations  in  the 
air  as  the  speaker's  voice  does  at  the  other  end.  It  is,  in- 
deed, an  extraordinary  feat  on  the  part  of  a  piece  of  flat 
metal  to  reproduce  all  the  variety  of  air  vibrations  for 
the  production  of  which  we  require  the  complex  machinery 
of  lungs,  vocal  cords,  mouth,  teeth,  tongue,  lips,  and  nose. 
It  is  evident  that  if  the  proper  vibratory  motion  can  be 
given  to  a  metal  disc,  by  any  means,  the  disc  will  speak. 
The  required  vibrations  are  far  too  complex  to  be  imitated 
by  any  purely  mechanical  arrangement,  although  an 
American,  some  twenty  years  ago,  did  construct  a  speak- 
ing machine,  by  closely  imitating  the  arrangement  of  our 
human  organs  of  speech.  While  the  machinery  was  most 
ingenious,  and  was  controlled  by  a  keyboard,  similar  to 
that  of  a  piano,  but  used  for  the  opening  and  closing  of 

141 


ELECTRICITY  REPRODUCES    SOUND 

valves,  etc.,  and  while  the  results  were  most  remarkable, 
yet  many  words  were  very  indistinct,  and  all  the  sounds 
were  too  uniform  and  drawling.  The  only  way  in  which 
we  can  give  a  metal  disc  the  proper  vibrations  is  by  either 
directly  speaking  in  front  of  it,  or  by  communicating  to 
it  these  vibrations  already  given  to  another  disc. 

In  the  phonograph  we  speak  against  a  very  thin  glass 
disc  or  diaphragm,  which,  by  means  of  an  attached  cutter, 
makes  little  indentations  on  a  rotating  cylinder  of 
specially  prepared  wax.  The  disc  may  again  be  made  to 
reproduce  the  speech  by  rotating  the  cylinder  and  allow- 
ing the  point  of  a  connecting  lever  to  bob  up  and  down, 
as  it  were,  in  the  indents,  and  thus  set  the  attached  disc 
once  more  vibrating,  exactly  as  it  did  on  the  first  occasion 
when  influenced  by  the  speaker's  voice. 

We  can  now  imagine  one  metal  disc  in  London  vibrat- 
ing in  sympathy  with  a  similar  disc  in,  say,  Glasgow,  pro- 
vided we  can  pass  on  the  vibrations  from  the  one  disc  to 
the  other.  Of  course,  a  direct  connection  of  a  stretched 
wire  of  vibrating  molecules  is  quite  out  of  the  question, 
as  already  explained,  but  a  very  simple  way  out  of  the 
difficulty  is  found  with  the  aid  of  an  electric  current. 
The  speaker  talks  against  a  little  disc  of  iron,  which  we 
may  imagine  as  being  a  somewhat  elastic  lid  to  a  metal 
box  filled  with  powdered  carbon.  The  current  on  its  way 
from  a  battery  to  the  line  wire  has  to  pass  through  the 
carbon ;  it  is  as  though  a  short  piece  of  the  wire  had 
been  cut  out,  and  this  box  of  carbon  inserted  in  the 
space.  The  powdered  carbon  offers  a  great  resistance  to 
the  passage  of  the  current,  but  if  the  carbon  is  com- 
pressed, even  very  slightly,  it  permits  more  current  to 

142 


ELECTRICITY   REPRODUCES    SOUND 

pass,  and  the  speaker,  by  speaking,  sets  up  air  vibrations, 
and  causes  such  pressure  on  the  disc  and  the  enclosed 
carbon.  The  variations  of  this  pressure  cause  an  ever- 
varying  current  to  pass  out  from  the  battery  through  the 
carbon  and  along  the  line  wire.  One  may  imagine  it  as  an 
undulatory  current  having  great  variety  of  waves,  and 


VI 


FIG.  9 

THE  PRINCIPLE  OF  THE   TELEPHONE 

The  current  from  the  battery  (B)  passes  through  the  powdered  carbon 
in  the  transmitter  (T)  and  goes  over  the  line  wire  to  the  distant  receiver 
(R).  The  current  is  controlled  by  the  vibrations  of  the  transmitter,  as 
explained  in  the  text. 

when  this  reaches  the  distant  end  of  the  wire,  it  is  led 
through  the  small  coil  of  an  electro-magnet,  in  front  of 
which  is  placed  a  metal  disc,  similar  to  that  in  the  trans- 
mitter at  the  sending  end.  The  metal  disc  will  be 
attracted  by  the  electro-magnet  in  degree,  according  to 
the  current  passing.  In  this  way  the  disc  in  the  receiver 


ELECTRICITY  REPRODUCES    SOUND 

is  set  into  motions  exactly  similar  to  those  of  the  disc  at 
the  speaker's  end.  When  the  listener  places  the  little 
disc  close  to  his  ear,  the  disc  in  turn  sets  the  air  into 
exactly  similar  vibrations  to  those  which  the  speaker  is 
producing  in  front  of  the  sending  disc,  and  therefore  the 
speech  is  heard  just  as  though  the  speaker's  voice  was 
directly  operating  on  the  listener's  tympanum  or  ear-drum. 
We  have,  therefore,  in  the  telephone  the  speaker's  voice 
controlling  the  battery  current,  which,  on  reaching  the 
distant  receiver,  produces  a  varying  magnetic  field,  thus 
influencing  a  little  iron  disc,  and  thus  setting  it  into 
exactly  similar  motion  to  the  controlling  disc. 

This  is  only  a  very  general  description  ;  there  are  other 
details  which  we  need  only  mention  in  passing.  When  the 
telephone  is  supplied  with  electricity  from  a  small  primary 
battery,  the  current  passes  through  a  small  induction  coil 
and  is  intensified  in  pressure.  Then  there  is  the  little 
electro -magnetic  machine  (a  small  dynamo),  which  is 
driven  by  a  handle,  and  sends  out  a  powerful  current  to 
operate  the  receiver's  bell.  As  this  bell  is  only  for  calling 
attention,  it  is  automatically  switched  out  of  the  circuit 
while  speaking.  When  that  part  of  the  instrument 
carrying  the  transmitter  and  receiver  is  lying  at  rest  on 
its  stand,  the  end  of  the  line  wire  is  in  contact  with  the 
bell  circuit,  but  as  soon  as  the  spoaking  part  is  lifted  the 
holder  rises  by  a  spring,  and  in  so  doing  it  switches 
the  line  wire  to  the  telephone  proper. 

In  the  first  form  of  telephone  in  which  this  powdered 
carbon  was  used,  the  little  metal  box,  or  case,  containing 
it  was  fixed  to  the  wall  instrument,  and  as  the  powder 
would  keep  gravitating  to  the  bottom  of  the  enclosing 

144 


USEFUL   INVENTION 

case,  the  speaker  was  requested  to  shake  or  turn  the  case 
occasionally.  Such  instructions  are  very  apt  to  be  over- 
looked, but  by  fixing  the  transmitter  in  one  piece  with 
the  receiver,  which  was  formerly  the  only  part  one  hung 
up  and  took  down  to  operate  the  switch,  the  speaker  is 
made  to  shake  up  the  carbon  in  the  transmitter  each  time 
he  uses  the  instrument  without  receiving  any  instructions 
to  do  so.  By  improvements  recently  made  in  the  trans- 
mitter it  is  now  unnecessary  to  move  or  turn  it  in  any 
way  to  maintain  its  efficiency.  It  is  of  interest  to  note 
that  this  transmitter  with  the  granular  carbon,  which  is 
now  in  full  command  of  the  field,  was  invented  by  an 
English  clergyman  named  Runnings.  Two  other  very 
useful  inventions  made  by  clergymen  are  the  power-loom 
and  the  hosiery-machine. 

At  the  time  of  writing  the  first  edition  of  the  present 
volume,  each  telephone  in  use  in  this  country  had  its  own 
primary  battery  beside  it.  But  in  America  it  had  been 
suggested  many  years  previously  to  supply  all  the  current 
from  a  central  battery  at  the  exchange,  and  dispense  with 
the  individual  batteries  at  the  subscribers'1  instruments.  In 
this  connection  the  following  remark  was  made  in  the  first 
edition :  "  It  seems  probable  that  all  telephones  will 
someday  be  worked  from  a  central  battery  at  the  ex- 
change, although  this  system  has  not  found  much  favour 
as  yet.1'  Since  that  time  many  exchanges  have  been 
arranged  on  the  central-battery  system  with  complete 
success. 

Through  the  courtesy  of  the  National  Telephone  Com- 
pany in  Glasgow  I  have  had  an  opportunity  of  seeing  the 
working  of  one  of  the  most  modern  exchanges  on  the 
K  145 


TELEPHONE  EXCHANGES 

central-battery  system.  Before  describing  this  exchange, 
a  few  preliminary  remarks  may  be  helpful. 

Originally  the  telephone  was  used  merely  for  speaking 
between  two  particular  places,  just  as  an  ordinary  speak- 
ing-tube is  used.  It  may  be  mentioned  in  passing  that 
the  general  public  looked  upon  the  telephone  as  a 
scientific  toy  at  first.  However,  it  soon  became  apparent 
that  if  all  the  telephone  lines  passed  through  one  public 
office,  it  would  be  possible  to  connect  any  two  of  the 
distant  instruments  together.  Prior  to  this  time  the 
Post  Office  had  given  intercommunication  between  private 
telegraph  lines  using  the  old  ABC  dials.  No  doubt  it 
was  this  fact  that  suggested  the  Telephone  Exchange. 

The  first  exchanges  were  very  small,  so  that  the  con- 
necting arrangements  were  very  simple.  The  telephone 
users  became  known  as  subscribers,  as  they  had  to  pay  a 
subscription  or  rent  to  the  company  who  supplied  the 
telephone  instruments  and  undertook  to  make  all  the 
necessary  connections  so  that  they  could  converse  with 
all  the  other  subscribers. 

When  one  wishes  to  be  able  to  connect  a  portable 
electric  lamp  to  several  places  in  a  house,  one  gets  the 
electrician  to  bring  the  ends  of  the  wires,  carrying  the 
current,  to  a  convenient  position  on  the  wall.  The  wires 
are  then  attached  to  two  little  sockets,  and  the  portable 
lamp  is  provided  with  two  small  fingers  or  plugs  which 
fit  into  these  sockets,  and  can  be  withdrawn  at  will.  The 
same  idea  is  made  use  of  in  connecting  one  pair  of  tele- 
phone wires  to  another  pair. 

In  the  early  days  only  one  wire  was  used  for  telephony, 
its  two  ends  dipping  into  the  earth  at  the  extremities 

146 


TELEPHONE  EXCHANGES 

just  as  telegraph  lines  of  the  present  day  are  arranged. 
All  the  subscribers'  wires  were  finished  off  with  a  little 
socket  or  "jack."  These  jacks  were  arranged  close 
together  in  a  table.  When  the  exchange  operator  was 
asked  to  connect  one  subscriber  to  another,  she  used  a 
short  length  of  flexible  wire  having  a  plug  on  each  end. 
Placing  one  plug  in  the  jack  belonging  to  the  first  sub- 
scriber, and  the  second  plug  in  that  of  the  other  sub- 
scriber, she  united  their  wires  and  enabled  them  to  carry 
on  conversation. 

In  the  early  days,  when  there  were  only  a  few  hundred 
subscribers,  a  telephone  exchange  was  comparatively 
simple.  A  modern  exchange  may  have  to  deal  with  as 
many  as  ten  or  twelve  thousand  subscribers,  and  in  order 
to  provide  means  of  connecting  together  any  two  of  that 
great  congregation  of  wires,  a  great  deal  of  ingenious 
planning  has  been  necessary.  It  will  be  of  interest  there- 
fore to  see  the  working  of  a  modern  exchange. 

I  may  remark  in  passing  that  it  will  be  apparent  to  all 
that  a  subscriber  cannot  call  to  an  operator,  "  Please  con- 
nect me  to  Mr.  John  Smith."  The  subscriber  must  look 
up  the  Telephone  Directory  and  state  merely  the  number 
by  which  Mr.  John  Smith  is  known.  We  are  just  so 
many  numbers  to  the  telephone  operator. 

Until  within  recent  years,  one  was  able  to  recognise  a 
telephone  exchange  by  the  great  congregation  of  wires 
over  the  top  of  the  building.  To-day  there  is  no  such 
conspicuous  sign,  and  one  might  pass  a  modern  exchange 
without  suspecting  that  it  was  such.  This  change  is  not 
accounted  for  by  the  advent  of  wireless  telephony,  which 
by  the  way  will  occupy  a  special  field  of  its  own,  and  as 


TELEPHONE   EXCHANGES 

far  as  one  can  see  at  present  it  will  not  come  into  com- 
petition with  ordinary  telephony.  The  reason  of  the 
change  referred  to  is  much  simpler.  It  is  merely  that 
the  congregation  of  wires  has  been  carried  along  under 
the  ground  instead  of  overhead.  There  are  many  advan- 
tages in  this  change. 

Each  cable  may  contain  as  many  as  twelve  hundred 
wires.  These  are  all  carefully  insulated  from  one  another 
and  protected  on  the  outside  by  a  heavy  lead  tube.  It 
is  common  practice  to  have  six  hundred,  or  even  eight 
hundred  pairs  of  wires  in  one  cable.  Each  subscriber 
requires  a  pair  of  wires  to  give  a  complete  circuit  for  his 
telephone,  as  the  original  plan  of  an  earth  circuit  has 
been  dispensed  with,  as  already  mentioned. 

I  have  been  amused  in  noting  the  different  ideas  that 
friends  have  formed  of  the  interior  of  a  telephone  ex- 
change. Some  have  even  pictured  a  large  hall  with  a 
multitude  of  telephone  instruments,  each  instrument 
representing  the  exchange  end  of  a  subscriber's  wire. 
However,  most  of  the  public  have  clearer  ideas  to-day. 
Photographs  of  the  interiors  of  some  exchanges  have 
been  published  in  the  public  journals. 

We  are  all  familiar  with  the  subscribers1  instruments 
in  their  homes  and  offices.  We  may  picture  the  wires 
from  six  hundred  different  subscribers'  instruments  all 
coming  together  and  passing  into  one  cable  which  is 
buried  under  the  streets.  The  other  end  of  the  cable 
comes  up  under  the  telephone  exchange.  Here  we  find 
several  similar  cables  coming  through  the  floor  of  the 
apparatus-room. 

The  amateur  electrician  finds  it  quite  a  task  to  separate 

148 


TELEPHONE   EXCHANGES 

the  ends  of  a  small  cable  containing  half  a  dozen  wires 
and  find  the  two  ends  of  the  same  wire.  Imagine  what 
it  must  be  to  separate  a  cable  of  twelve  hundred  wires ! 

The  first  thing  the  telephone  engineer  has  to  do  is  to 
separate  these  wires  and  fix  the  end  of  each  wire  to  a 
suitable  connection  upon  one  side  of  the  "main-distributing 
frame.11  He  takes  the  wires  just  as  they  come  without 
considering  the  number  of  the  subscriber.  After  getting 
these  securely  fixed,  he  attaches  to  each  certain  safety 
devices.  There  is  some  risk  of  a  telephone  wire  getting 
in  contact  with  an  electric-light  wire  and  conducting  a 
heavy  current  into  the  exchange.  Two  of  the  safety 
devices  are  to  protect  the  apparatus  in  the  exchange 
against  the  entrance  of  any  such  current.  These  pro- 
tectors consist  of  a  fuse  and  a  heat-coil.  They  give  way 
under  the  heat  produced  by  a  heavy  current,  and  as  soon 
as  they  break  they  cut  the  circuit  or  send  the  intruding 
current  to  earth.  The  third  safety  device  is  to  protect 
the  exchange  apparatus  against  lightning,  should  it 
happen  to  strike  a  telephone  wire.  This  lightning-arrester 
consists  essentially  of  a  small  air-gap  across  which  the 
lightning  charge  can  jump  to  an  earth  wire,  whereas  the 
ordinary  telephone  current  cannot  cross  this  air-gap,  and 
has  to  keep  to  its  continuous  path.  The  lightning,  on 
the  other  hand,  finds  it  easier  to  take  this  short  cut  to 
earth  rather  than  go  through  the  apparatus  in  the  ex- 
change. The  difference  of  behaviour  between  the  battery 
current  and  the  lightning  discharge  is  due  to  the  fact 
that  the  former  is  impelled  by  a  low  electrical  pressure, 
while  the  electrical  pressure  of  the  latter  is  millions  of 
times  greater. 

149 


TELEPHONE   EXCHANGES 

After  getting  each  wire  securely  fixed  with  these  safety 
devices,  the  wires  are  continued  over  to  the  other  side  of 
the  distributing  frame,  each  wire  being  taken  from  this 
point  to  a  second  frame  in  numerical  rotation.  No.  1 
subscriber's  wire  is  now  in  the  first  position  on  this  frame, 
and  so  on  with  the  others.  These  are  extended  to  a  third 
frame  carrying  apparatus  the  use  of  which  we  shall  under- 
stand better  when  we  have  seen  what  is  taking  place  in 
the  switch-room^  where  all  the  connecting  and  disconnect- 
ing of  the  subscribers1  lines  is  carried  on. 

When  we  enter  this  room  we  see  an  upright  board 
extending  right  round  the  room.  (See  photograph  facing 
page  146.)  This  is  the  board  which  holds  all  the  little 
sockets  or  "jacks"  representing  the  ends  of  the  sub- 
scribers' wires. 

We  find  the  operators  sitting  in  a  row  around  the 
room,  facing  this  upright  board,  as  may  be  seen  in  the 
photograph.  Each  of  these  young  ladies  has  a  very 
light  telephone  receiver  held  against  her  ear  by  a  suitable 
fastening  around  her  head.  The  transmitter  of  her 
telephone,  which  is  supported  by  a  light  frame  hung 
upon  her  shoulders,  has  a  long  funnel  coming  close  up  to 
her  mouth.  Standing  in  the  switch-room,  one  scarcely 
hears  that  any  conversation  is  taking  place  at  all. 

First  of  all  we  had  better  get  a  general  idea  of  the  opera- 
tors1 duties.  They  are  to  attend  to  all  the  calls  made 
by  the  subscribers  and  make  the  necessary  connections 
between  subscribers,  disconnecting  them  when  requested. 
An  operator  must  be  able  to  connect  the  subscriber  calling 
with  any  number  requested.  This  means  that  each  opera- 
tor must  be  able  to  reach  from  No.  1  socket  or  jack  to 


TELEPHONE   EXCHANGES 

No.  10,000.  It  is  necessary  on  this  account  to  bring  all 
the  jacks  into  as  small  a  space  as  possible,  consistent 
with  efficient  construction.  The  space  required  makes  a 
board  opposite  which  three  operators  may  sit  with  com- 
fort and  yet  so  arranged  that  each  may  reach  to  any  one 
of  the  ten  thousand  jacks  on  the  board. 

While  each  of  these  operators  could  connect  any  two 
of  the  jacks  with  a  flexible  cord,  it  must  be  clear  to  all 
that  these  three  operators  are  not  going  to  attend  to  the 
calls  of  the  whole  ten  thousand  subscribers.  One  hundred 
subscribers  will  keep  an  operator  fairly  busy,  but  she  can 
connect  any  of  these  with  every  other  subscriber  asked  for. 

To  answer  the  calls  of  the  whole  ten  thousand  sub- 
scribers will  require  about  one  hundred  operators  each 
attending  to  about  one  hundred  subscribers.  There  is 
nothing  for  it  but  to  fit  up  duplicate  boards  each  contain- 
ing the  whole  subscribers'1  jacks,  and  let  every  three 
operators  have  a  complete  board.  We  may  picture  the 
pair  of  wires  of  No.  1  subscriber  coming  up  from  the 
apparatus-room  and  entering  the  switch-board ;  at  the  first 
section  they  are  fastened  to  No.  1  jack,  then  passing  on  to 
the  next  section  they  are  fastened  to  another  similar  jack 
also  marked  No.  1.  So  on  the  wires  go  through  the  whole 
long  board  around  the  room,  being  tapped  at  each  section 
and  connected  to  a  socket  or  jack  fixed  there.  The  whole 
arrangement  is  called  the  multiple  board  because  of  this 
multiplication  of  jacks  for  each  subscriber's  line. 

We  are  ready  to  see  how  the  subscriber  is  to  com- 
municate with  the  operator.  Several  different  plans 
have  been  tried.  I  can  remember  in  the  early  days  we 
used  to  go  forward  to  our  telephone  instruments  and 


TELEPHONE   EXCHANGES 

"  ring  up  "  the  operator.  That  is  to  say,  we  turned  the 
handle  of  the  little  magneto-electric  machine  just  as  we 
did  when  ringing  a  subscriber  after  being  connected. 
Some  subscribers  fondly  imagined  that  they  were  actually 
ringing  a  bell  in  the  exchange,  and  if  they  did  not  get 
immediate  attention  they  would  continue  to  "  ring  like  a 
house  on  fire/'  I  used  to  ask  these  friends  what  sort  of 
pandemonium  they  thought  a  telephone  exchange  must 
be  like.  Imagine  hundreds  if  not  thousands  of  bells  all 
ringing  at  one  time  in  one  room.  These  impatient  sub- 
scribers were  quite  disappointed  to  learn  that  all  their 
high-pressure  energy  merely  caused  a  very  small  lever  to 
drop  the  shutter  of  a  little  indicator  and  expose  the 
number  of  the  subscriber  making  the  call.  After  this 
almost  noiseless  operation  was  performed,  the  remainder 
of  the  current  which  was  intended  to  waken  up  the 
operator  merely  caused  the  tiny  lever  to  move  a  small 
fraction  of  an  inch. 

Another  plan  adopted  to  give  subscribers  a  prompt 
means  of  communicating  with  the  operator  was  to  have 
the  operator  always  listening  on  a  public  call-wire.  This 
wire  passed  through  a  certain  section  of  the  town,  and 
branch  lines  were  dropped  from  it  into  the  subscribers1 
offices  or  homes.  As  many  as  sixty  subscribers  would  be 
connected  to  one  call-wire.  The  telephone  instruments 
were  not  connected  directly  to  this  wire,  but  as  long  as 
the  subscriber  depressed  a  button  on  his  instrument  he 
switched  his  telephone  on  to  this  public  call-wire.  The 
advantage  was  that  he  could  get  in  touch  with  the  opera- 
tor at  any  moment.  The  disadvantage  was  that  a  number 
of  subscribers  might  all  attempt  to  give  calls  at  the  same 

152 


By  permission  of  the  Automatic  Electric  Co., 
of  Chicago. 

How  AN  AUTOMATIC  TELEPHONE 
WORKS. 

<i)  In  Automatic  Telephone  Exchan- 
ges there  are  no  operators.  Every 
subscriber  has  an  instrument  as  shown 
in  the  above  illustration,  and  if  he 
wishes  to  be  connected,  say,  to  sub- 
scriber No.  357,  he  merely  places  his 
finger  into  the  hole  marked  3  and  turns 
the  dial  round  as  far  as  it  will  go.  He 
then  does  the  same  with  Nos.  5  and  7, 
and  is  then  connected  through  to  the 
other  subscriber. 


By  permission  of  the  Automatic  Electric  Co., 
of  Chicago. 

(2)  At  the  Exchange  end  of  the  wire  is  a  very 
ingenious  piece  of  apparatus  called  a  Selector,  as 
shown  in  the  photograph.  Every  subscriber's  line 
has  one  of  these  selectors,  whose  duty  is  to  make 
the  necessary  connection,  which  it  does  without 
the  usual  girl  operator. 


TELEPHONE   EXCHANGES 

time,  and  unfortunately  many  of  them  seemed  to  think 
that  whoever  would  cry  the  loudest  would  get  the  best 
attention.  The  result  was  that  the  poor  operator  was 
often  at  her  wits'*  end  to  make  head  or  tail  of  the  jumble 
of  noises.  This  call-wire  system  is  most  convenient  in 
districts  where  the  subscribers  are  not  too  numerous  and 
where  there  is  no  great  rush  of  business. 

Another  plan  was  to  give  each  operator  an  answering 
jack  for  each  subscriber  to  whom  she  had  to  attend. 
These  were  sockets  or  jacks  similar  to  those  in  the  multiple 
board,  but  additional  to  them.  These  answering  jacks 
were  grouped  together  below  the  others  right  in  front  of 
the  operator.  Beneath  each  answering  jack  there  was  a 
tiny  electric  glow  lamp,  in  diameter  about  the  size  of  a 
large  pea.  At  the  other  end  of  the  line  the  subscriber 
had  a  button  on  his  instrument,  which  if  depressed  caused 
the  little  lamp  in  the  exchange  to  light  up.  In  this  way 
the  operator  knew  when  any  of  her  one  hundred  subscribers 
wanted  to  speak  to  her. 

The  latest  plan  is  really  an  improvement  on  the  last- 
mentioned.  The  operator  still  has  the  answering  jacks 
and  the  little  signal  lamps,  but  things  have  been  made 
very  easy  for  the  subscriber.  He  has  not  to  trouble 
about  any  signalling.  He  merely  lifts  his  telephone  off 
the  hook,  and  this  action  causes  the  signal  lamp  to  glow. 
With  the  latest  methods  the  operator  is  able  to  answer 
within  five  seconds,  so  the  subscriber  will  doubtless  think 
she  has  been  waiting  his  call  just  as  the  operator  on  the 
call-wire  used  to  do.  Indeed,  one  gentleman  using  this  new 
system  has  told  me  that  the  operator  answers  so  quickly 
sometimes  that  he  suddenly  forgets  what  he  was  about  to  say. 

'53 


TELEPHONE   EXCHANGES 

It  is  worth  while  enquiring  what  really  happens  when 
the  subscriber  lifts  his  telephone  off  its  support.  The 
support,  being  freed  of  the  weight  of  the  telephone, 
springs  up  and  completes  the  subscribers  circuit  with 
the  exchange.  This  causes  a  current  from  the  large 
battery  at  the  exchange  to  operate  a  signalling  instru- 
ment attached  to  the  subscriber's  line,  on  the  third  frame 
mentioned,  in  the  apparatus-room.  This  little  signalling 
instrument,  called  a  relay,  consists  of  an  electro-magnet 
which  attracts  an  armature  to  it  and  thus  switches  on 
the  necessary  current  to  light  up  the  small  lamp  beside 
his  answering  jack  on  the  operator's  board.  As  long  as 
the  subscriber  keeps  his  telephone  off  the  hook  the  little 
relay  in  the  apparatus-room  will  keep  the  current  switched 
on  to  the  lamp. 

When  the  operator  inserts  the  plug,  which  is  attached 
to  one  end  of  her  connecting  wire,  into  the  answering 
jack,  this  lamp  goes  out.  The  insertion  of  the  plug  in 
answering  the  call  puts  current  on  to  a  second  relay 
arranged  beside  the  first  one  in  the  apparatus-room. 
This  switches  the  current  off  the  first  relay,  causing  the 
lamp  to  go  out  as  mentioned,  and  the  insertion  of  the 
plug  at  the  same  time  brings  on  the  necessary  lighting 
current  for  the  signalling  lamp  representing  the  connect- 
ing wire.  There  are  two  lamps,  one  representing  each 
side  of  the  connecting  wire.  The  two  ends  of  this  con- 
necting wire  come  up  through  the  operator's  table  and 
the  plugs  stand  upright  in  front  of  her.  The  flexible 
wire  hangs  down  beneath  the  table  until  the  plugs  are 
lifted,  when  it  comes  through  the  table.  A  weight  sus- 
pended beneath  the  table  keeps  the  flexible  wire  always 


TELEPHONE   EXCHANGES 

taut,  and  pulls  it  back  through  the  table  when  the 
operator  frees  the  plugs  from  the  jacks. 

So  far  the  operator  has  used  only  one  leg  of  the  con- 
necting wire.  She  has  inserted  this  in  the  answering 
jack,  whose  light  glowed.  By  moving  a  small  lever  into 
what  is  called  "  the  listening  position "  she  switches  her 
own  telephone  on  to  the  calling  subscriber  and  learns 
from  him  the  number  of  the  subscriber  to  whom  he 
wishes  to  speak.  The  operator  now  lifts  the  second  plug 
on  the  connecting  wire  and  puts  it  into  the  jack  of  the 
number  wanted.  She  then  moves  the  little  lever  from 
"  the  listening  position  "  to  "  the  ringing  position,"  and 
this  causes  an  electric  current  from  the  apparatus-room 
to  reach  the  subscriber's  telephone  and  his  bell  rings. 
The  ringing  current  is  supplied  by  a  generator  driven  by 
a  motor.  The  operator  holds  the  key  over  to  the  ringing 
position  for  a  second  or  so,  then  releases  it.  Until  the 
subscriber  wanted  answers  the  ring  thus  given,  the  lamp 
on  that  side  of  the  connecting  wire  glows,  but  imme- 
diately he  takes  the  telephone  off  the  hook  the  lamp 
goes  out.  This  gives  the  operator  intimation  that  the 
subscriber  wanted  has  answered  the  call.  The  operator 
knows  that  both  subscribers  have  their  telephones  off  the 
hooks,  and  she  leaves  them  connected. 

If  one  lamp  glows  while  the  other  remains  out,  she  still 
leaves  them  connected,  for  very  probably  one  subscriber 
has  merely  put  down  his  telephone  while  he  goes  to  make 
some  inquiry.  When  both  lamps  glow,  this  is  accepted  as 
thesignal  to  disconnect.  The  operator  is  entitled  to  presume 
that  they  have  finished  as  they  have  both  laid  down  their 
telephones.  She  therefore  withdraws  the  connecting  plugs. 


TELEPHONE   EXCHANGES 

It  will  be  observed  that  the  subscriber  has  not  to  "  call 
off."  This  is  always  a  trouble  in  other  systems,  for  a  sub- 
scriber omitting  to  call  off  is  supposed  to  be  "  engaged." 
The  only  possible  chance  of  a  subscriber  being  left 
"  engaged "  after  he  has  finished  is  if  he  goes  away  and 
leaves  his  telephone  off  the  hook.  Even  this  contingency 
is  provided  for.  It  would  seem  hopeless  to  get  him,  as 
the  operator  cannot  ring  his  bell  so  long  as  his  telephone 
is  off  the  hook.  She  reports  the  matter  to  a  test  clerk, 
who  switches  on  "  the  howler."  This  produces  a  howling 
sound,  not  unlike  a  syren,  in  the  subscriber's  telephone. 
This  calls  the  attention  of  the  subscriber  to  his  careless- 
ness in  leaving  his  telephone  off  the  hook. 

It  is  obvious  that  two  subscribers  at  different  boards 
may  call  for  the  same  number  at  the  one  time.  What 
is  to  prevent  an  operator  connecting  a  third  party  to  a 
line  already  in  use?  She  can  tell  by  touching  the  sub- 
scriber's jack  with  the  connecting  plug  before  she  inserts 
it.  If  she  hears  a  clicking  sound  in  her  own  telephone 
she  knows  that  the  line  is  already  connected  elsewhere, 
so  she  intimates  "engaged  sorry"  to  the  subscriber 
asking  for  the  number. 

Other  operators,  at  a  separate  table,  deal  with  con- 
nections to  other  exchanges,  but  we  need  not  trouble  with 
more  detail  as  the  general  principle  is  the  same  as  that 
just  described.  There  is,  of  course,  this  difference,  that 
the  two  subscribers'*  jacks  which  are  to  be  connected  lie 
in  different  exchanges.  This  necessitates  the  use  of  a 
junction  line,  one  end  of  which  is  in  the  one  exchange 
and  the  second  in  the  distant  exchange.  These  calls  are 
described  as  junction  calls.  One  interesting  feature  in 

'56 


TELEPHONE   EXCHANGES 

connection  with  these  calls  is  that  when  the  operator  puts 
down  the  key  to  ring  the  subscriber  wanted,  it  is  auto- 
matically held  down.  It  is  so  arranged  that  the  ringing 
current  from  the  generator  is  cut  off  and  put  on  at  the 
end  of  every  few  seconds,  after  the  manner  of  some  alarm 
clocks,  until  the  subscriber  wanted  lifts  his  telephone  off 
the  hook.  Immediately  he  does  this  the  current  which 
holds  the  key  down  is  automatically  switched  off  and  this 
in  turn  cuts  off  the  ringing  current.  In  this  way  the 
operator's  time  is  not  wasted  waiting  the  reply  of  a 
dilatory  subscriber,  while  the  bell  of  his  telephone 
continues  to  ring  until  he  answers.  Then  there  are 
trunk  calls,  which  signify  connections  requiring  to  be  made 
between  two  subscribers  who  are  in  different  towns.  A 
subscriber  in  London  may  converse  with  a  friend  in 
Scotland  or  France,  and  so  on. 

There  is  one  point  which  is  sure  to  be  of  interest  to 
telephone  users.  Instead  of  renting  the  telephone  for  a 
certain  annual  subscription,  it  is  becoming  common  to 
charge  so  much  per  thousand  calls.  How  in  the  world  is 
an  operator  going  to  keep  count  of  all  the  calls  each  of  her 
one  hundred  subscribers  makes  in  a  day  ?  She  is  kept 
busy  enough  connecting  and  disconnecting  subscribers 
without  attempting  any  system  of  book-keeping.  Again 
the  obliging  automaton  comes  to  her  assistance.  Down 
in  the  apparatus-room  each  subscriber's  wire  is  provided 
with  a  tiny  meter  or  register.  Any  one  who  is  familiar 
with  the  small  cyclometers  put  upon  cycle  wheels,  for 
counting  the  mileage,  will  understand  the  general  principle. 
A  train  of  wheels  turns  the  figures  on  an  indicator.  But 
the  meter  must  not  work  every  time  the  subscriber  lifts  his 

'57 


THE  AUTOMATIC  TELEPHONE 

telephone  off  the  hook  to  call  the  exchange.  The  number 
he  wants  may  be  engaged,  and  he  will  not  be  willing  to 
pay  if  he  has  not  obtained  the  connection  he  asked  for. 
It  is  the  operator,  therefore,  who  actuates  the  meter. 
When  a  subscriber  has  got  his  message  through,  the  opera- 
tor depresses  a  small  key  or  button  in  circuit  with  the 
connecting  wire  she  is  using.  This  sends  a  current  to  the 
meter  of  the  calling  subscriber  and  registers  one  call 
against  him.  The  telephone  subscriber  therefore  pays  for 
his  calls  on  the  same  principle  as  he  pays  for  his  gas  or 
electricity. 

Each  operator  has  also  a  meter  which  registers  the 
total  number  of  calls  she  attends  to  each  day.  This, 
however,  is  merely  for  the  use  of  the  telephone  manager. 

It  will  be  remembered  that  there  are  no  batteries 
at  the  subscriber's  telephone.  The  whole  of  the  necessary 
current  is  supplied  from  the  exchange.  About  one  dozen 
large  accumulators  serve  for  everything.  These  are 
charged  by  means  of  suitable  dynamos.  One  advantage 
is  that,  no  matter  how  long  a  conversation  may  be  con- 
tinued, the  current  remains  constant.  The  primary 
battery,  on  the  other  hand,  used  to  give  trouble,  as 
its  current  fell  off  very  quickly  if  kept  too  long  on  the 
line  without  a  rest.  There  is  no  doubt  that  the  central- 
battery  system  has  come  to  stay — at  least  until  some 
other  newer  method  makes  its  appearance. 

In  the  United  States  of  America  there  are  several 
telephone  exchanges  which  are  worked  without  human 
operators,  the  connections  and  disconnections  being  made 
automatically.  One  of  these  exchanges  has  eight  thousand 
subscribers. 

158 


THE   AUTOMATIC  TELEPHONE 

The  method  of  calling  a  number  will  be  understood 
by  referring  to  the  left-hand  illustration  facing  page  152. 
The  legend  below  the  photograph  will  explain  the  action. 
The  electric  impulses  sent  out  by  the  subscriber  in  calling 
the  number  desired  operates  a  selector,  the  construction 
of  which  is  shown  in  the  right-hand  photograph  on  the 
same  page. 

When  the  subscriber  signals  the  number  of  hundreds  in 
the  directory  number  of  the  subscriber  he  wishes,  the 
centre  rod  in  the  selector  moves  up  three  sections  if  the 
number  signalled  is  in  the  three  hundreds.  This  upright 
rod  carries  with  it  a  little  arm  or  finger  which  is  to  make 
connection  with  the  other  subscriber's  line.  At  present 
we  have  imagined  it  to  be  raised  to  the  section  containing 
all  the  numbers  beginning  with  three  hundred.  The  next 
set  of  impulses  from  the  calling  subscriber  moves  the 
little  contact  finger  to  the  flat  or  row  containing  the 
number  wanted.  If  it  is  among  the  fifties  then  five 
impulses  are  received,  and  that  raises  the  finger  to  the 
fifth  row.  The  next  set  of  impulses  representing  the  units 
cause  the  rod  to  turn  round  and  bring  the  finger  along 
the  row  to  the  first,  second,  or  whatever  number  is 
required  among  the  fifties.  Thus  if  the  subscriber  signals 
the  numbers  three,  five,  and  seven  successively,  the  con- 
necting finger  will  rise  to  the  third  hundred,  the  fifth 
row,  and  the  seventh  line  in  that  row ;  his  telephone  will 
be  connected  to  No.  357. 

When  the  subscriber  who  originated  the  call  puts  his 
telephone  back  on  the  hook,  the  automaton  disconnects 
the  line  by  allowing  the  upright  rod  in  the  selector  to 
return  to  its  former  position  of  zero.  The  disadvantage 


THE    TELEGRAPHONE 

in  a  purely  automatic  exchange  is  that  the  Company 
lose  all  control  of  the  system.  To  take  an  illustration, 
we  may  suppose  that  subscriber  A  is  a  rather  eccentric 
individual,  and  because  he  has  a  grievance  against  sub- 
scriber B,  A  connects  his  telephone  to  that  of  B,  but 
does  not  ring  him.  So  long  as  A  leaves  this  connection, 
of  which  B  is  not  aware  and  which  he  could  not  dis- 
connect, so  long  will  no  one  else  be  able  to  call  B.  In 
other  words,  one  subscriber  can  purposely  hold  up  the 
line  of  another  subscriber  to  the  disadvantage  of  the 
latter. 

There  is  now  a  telephone  which  might,  by  the  un- 
initiated, be  supposed  to  possess  brains,  for  if  its  owner 
is  absent  when  a  friend  rings  him  up  it  will  accept  the 
message  on  its  own  account,  and  repeat  it  to  its  master  on 
his  return,  and  no  matter  how  long  he  is  in  returning,  or 
how  many  friends  have  confided  messages  to  it,  it  never 
suffers  from  loss  of  memory,  but  gives  a  correct  recital 
of  all  the  information  or  secrets  that  have  been  entrusted 
to  it. 

This  instrument  is  called  a  telegraphone,  and  its  general 
principle  may  be  briefly  stated.  If  one  pictures  for  a 
moment  the  telephone  transmitter  sending  out  a  varying 
current  to  the  distant  magnet,  as  described  in  the  earlier 
part  of  this  chapter,  and  if  one  recalls  how  the  magnet 
acted  upon  the  disc  or  diaphragm,  then  we  have  only  to 
replace  the  stationary  disc  by  an  iron  wire  passing  in  front 
of  and  slightly  touching  the  magnet,  the  wire  being  thus 
magnetised  by  the  influence  of  the  electro-magnet,  which 
is  varying  under  control  of  the  speaker's  voice.  The  wire 
therefore  receives,  as  it  were,  a  great  number  of  spots 

160 


TELEPHONE   WITH   A   MEMORY 

of  different  degrees  of  magnetisation,  which  it  is  capable 
of  retaining,  the  wire  being  made  of  mild  steel.  The  wire 
is  now  analogous  to  a  phonograph  cylinder  with  a  record 
upon  it.  The  reproduction  of  the  sound  is  very  easily 
understood  if  one  imagines  the  little  magnet  of  a  tele- 
phone receiver,  instead  of  being  magnetised  by  the  incom- 
ing current  from  a  distance,  being  now  merely  put  in 
contact  with  this  magnetised  wire,  which,  when  drawn 
across  the  electro-magnet,  imparts  similar  degrees  of 
magnetism  to  it.  The  magnet,  thus  influenced,  will  in 
turn  operate  an  ordinary  telephone  diaphragm,  and  thus 
set  up  similar  air  vibrations  to  those  originally  imparted 
to  the  telephone  that  used  the  wire  as  a  record. 

As  the  telegraphone  is  now  a  reliable  piece  of  ap- 
paratus, there  may  be  quite  a  large  commercial  field  for 
it.  How  much  more  reliable  to  have  a  clear-headed 
instrument  accept  a  message  and  redeliver  it  instead 
of  having  to  cross-examine  a  careless  servant  as  to  whether 
Mr.  So-and-so  said  this  or  that. 


161 


CHAPTER  XV 
WIRELESS   TELEPHONY 

The  telephone  receiver  in  wireless  telegraphy — Early  attempts  at 
transmitting  speech — Speaking  along  a  beam  of  light — Speech 
transmitted  between  two  parallel  wires — The  latest  methods. 

WHEN  considering  the  different  methods  of  pick- 
ing up  the  signals  in  wireless  telegraphy  we 
saw  that  one  convenient  arrangement  included 
a  telephone  receiver  in  which  the  operator  heard  a  series 
of  clicks  representing  the  Morse  code.     This  arrangement 
led  to  some  confusion  in  the  early  days  of  wireless  tele- 
graphy.    Newspaper   reporters   and   others  seeing   these 
experiments  believed  that  speech  was  being  transmitted. 

At  that  time  most  of  us  had  no  great  faith  in  wireless 
telephony  coming  into  practical  use  over  any  long  dis- 
tance. It  was  one  thing  to  send  signals  by  means  of 
sudden  disturbances  in  the  ether,  such  as  those  waves 
produced  by  a  torrent  of  sparks,  but  it  required  some- 
thing better  than  that  to  transmit  the  more  delicate 
alternating  current  used  in  telephony.  Indeed,  if  we  had 
to  depend  entirely  upon  the  spark  method  of  transmission, 
we  could  not  have  produced  an  efficient  wireless  telephone. 
With  the  introduction  of  continuous  trains  of  ether  waves, 
however,  it  became  possible  to  transmit  articulate  speech. 
It  is  true  that  a  wireless  telephone  existed  before  the 


THE  TELEPHONE  RECEIVER 

days  of  wireless  telegraphy,  but  as  this  consisted  practi- 
cally in  speaking  along  a  beam  of  light,  it  was  evident 
that  the  distance  over  which  this  might  be  used  must  be 
very  limited.  It  seemed  as  though  this  method  could 
remain  only  an  interesting  scientific  experiment.  This 
principle  has  been  adapted  for  short  ranges — such  as 
between  ferry-boats  and  the  shore. 

The  general  principle  of  the  foregoing  may  be  of  some 
interest.  The  telephone  had  not  been  invented  for  any 
length  of  time,  when  it  was  discovered  that  speech  might 
be  transmitted  along  a  beam  of  light.  The  beam  of 
light,  either  sunlight  or  electric  arc  light,  is  focussed  on 
to  a  little  flexible  mirror,  made  of  silvered  glass  or  mica. 
The  speaker's  voice  causes  this  little  mirror  to  vibrate, 
just  as  though  it  were  the  disc  or  diaphragm  in  a  tele- 
phone transmitter.  The  vibrations  of  the  mirror  disturb 
the  beam  of  light  which  it  reflects  towards  the  distant 
receiver,  where  it  falls  upon  a  selenium  cell.  This  cell 
possesses  the  strange  property  of  altering  its  electrical 
resistance  in  proportion  to  the  amount  of  light  falling 
upon  it.  We  may  picture  the  selenium  cell  as  being 
somewhat  analogous  to  an  ordinary  bell-push,  but  in- 
finitely more  sensitive.  You  may  press  a  bell-push  and 
allow  the  current  to  pass,  or  you  may  let  go  the  push  and 
stop  the  current,  but  the  selenium  cell  allows  different 
amounts  of  current  to  pass  according  to  the  amount  of 
light  falling  upon  it.  If  only  a  little  light  falls  upon 
the  selenium,  then  only  a  little  current  is  allowed  to  pass. 
An  increase  in  light  means  a  corresponding  increase  in 
current.  By  this  means  the  varying  beam  of  light  con- 
trols the  current  in  the  telephone  receiver,  so  that  the 

163 


A   BEAM   OF   LIGHT 

vibrations  of  the  little  mirror  at  the  speaking  station  are 
imitated  by  the  diaphragm  in  the  telephone  receiver.  In 
this  way  the  original  speech  is  reproduced  at  a  distance. 

It  is  interesting  to  note  that  in  the  experiments  made 
with  this  light-telephony  it  was  found  possible  to  speak 
from  both  stations  simultaneously,  the  two  beams  of  light 
not  interfering  with  one  another.  Speech  has  been  trans- 
mitted over  a  distance  of  about  eight  miles  by  this 
method. 

There  is  one  point  which  might  appear  to  be  a  diffi- 
culty. How  is  the  sending  station  to  focus  the  beam  of 
light  on  to  the  receiver  of  a  moving  ferry-boat  ?  This 
difficulty  is  not  a  real  one,  for  the  beam  of  light  will  have 
spread  out  to  a  breadth  of  several  hundred  yards  if  the 
distance  be  great.  The  action  is  all  the  more  remarkable 
as  only  a  very  small  portion  of  the  beam  of  light  will 
reach  the  receiver.  It  is  quite  obvious,  however,  that  the 
maximum  distance  over  which  this  system  may  be  used 
cannot  exceed  a  few  miles. 

In  the  chapter  on  wireless  telegraphy  I  have  referred 
to  the  early  system  used  by  Sir  William  Preece.  It  will 
be  remembered  that  the  principle  was  one  of  induction 
between  two  long  parallel  wires,  one  at  the  sending 
station  and  the  other  at  the  receiving  station.  It  was 
found  possible  not  only  to  send  signals,  but  to  transmit 
actual  speech  over  a  distance  of  several  miles. 

The  electric  current  sent  out  by  the  telephone  trans- 
mitter is  a  to-and-fro  or  alternating  current,  so  that 
every  variation  of  current  in  the  long  transmitting  wire 
induces  a  corresponding  current  in  the  distant  parallel 
wire  at  the  receiving  station.  The  one  disadvantage  is 

164 


SPEECH   TRANSMITTED 

that  the  length  of  the  parallel  wires  has  to  be  increased 
as  the  distance  between  the  stations  is  increased. 

An  installation  upon  this  plan  has  been  at  work  for 
many  years  between  the  lighthouse  on  an  island  called 
The  Skerries  and  the  mainland  on  the  coast  of  Anglesey. 
The  distance  is  a  little  short  of  three  miles,  and  under 
ordinary  circumstances  one  might  think  it  best  to  lay  a 
submarine  cable.  But  the  sea-bottom  at  this  point  is  so 
rough  and  the  tidal  currents  so  strong  that  a  cable  would 
be  quite  useless.  The  island  is  a  small  one,  but  it  was 
found  that  a  short  wire  of  less  than  half  a  mile  on  the 
i.sland,  with  a  parallel  wire  of  about  three  and  a  half 
miles  on  the  mainland,  was  sufficient  to  give  good  in- 
duction between  the  stations.  The  convenience  of  being 
able  to  carry  on  ordinary  conversation  between  the  light- 
house and  the  mainland  will  be  appreciated. 

While  the  ordinary  spark  discharge  was  useless  for 
transmitting  speech,  it  was  found  that  by  more  rapid 
sparking  arrangements  much  better  results  could  be  ob- 
tained. But  the  great  strides  which  have  been  made  in 
wireless  telephony  are  not  based  upon  a  spark  discharge. 
A  continuous  emission  of  ether  waves  is  produced  by 
rapid  electric  oscillations  in  an  aerial  wire,  and  this 
emission  is  controlled  by  the  speaker's  voice.  What 
happens  is  this. 

We  have  two  persons  separated  from  each  other  by 
many  miles,  and  without  any  connecting  wires  between 
the  two  places.  One  of  the  men  speaks  into  a  telephone 
transmitter,  the  connections  from  which  end  in  an  upright 
aerial  wire  at  his  own  station.  At  the  distant  station  the 
second  man  listens  at  a  telephone  receiver  connected  to  a 

165 


THE  LATEST  METHODS 

similar  and  local  aerial  wire.  The  speech  is  transmitted 
between  these  two  aerials  in  the  form  of  ether  waves. 
The  diaphragm  in  the  telephone  transmitter  sets  up  a 
to-and-fro  current  in  the  ordinary  telephone  circuit,  and 
this  current  is  made  to  act  upon  another  neighbouring 
circuit,  in  which  a  high-frequency  current  is  continuously 
surging.  The  variations  in  the  telephone  current  cause 
similar  variations  in  this  powerful  current.  These  electric 
oscillations  are  conducted  to  the  aerial  wire,  and  in  this 
way  the  surrounding  ether  is  disturbed.  Those  tther 
waves  travel  out  towards  the  receiving  station,  and  are 
intercepted  by  the  aerial  wire  at  that  distant  plac^. 
There  they  affect  a  suitable  wave-detector,  such  as  an 
electrolytic  cell.  By  this  means  a  local  battery  current 
is  controlled,  and  this  actuates  an  ordinary  telephone 
receiver.  In  this  way  the  original  speech  is  reproduced. 

Some  wireless  telephone  companies  have  been  guaran- 
teeing distances  up  to  one  hundred  miles  for  several 
years  back.  It  is  now  possible  to  speak  over  a  distance 
of  about  two  hundred  miles. 

As  proof  of  the  importance  of  wireless  telephony,  I 
may  state  that  the  United  States  Navy  have  equipped  a 
number  of  their  battleships  with  installations  for  speak- 
ing up  to  distances  of  twenty-five  miles.  For  greater 
distances  more  power  would  be  required.  The  problem 
of  tuning  to  prevent  interference  is  of  even  greater  im- 
portance in  wireless  telephony  than  in  telegraphy. 


166 


CHAPTER  XVI 
INDUCTION  COILS  EXPLAINED 

What  induction  means — How  an  induction  coil  works — What  happens 
in  the  coil— An  analogy— Modern  improvements. 

IF  one  holds  on  to  the  handle  end  of  a  poker  while  the 
other  end  is  placed  in  a  fire  one  soon  feels  considerable 
heat  passing  to  the  hand,  till  the  metal  ultimately 
becomes  too  hot  to  hold  any  longer.  We  may  say  that 
the  poker  has  conducted  heat  from  the  fire  to  the  hand, 
and  in  the  same  way  we  may  think  of  the  telegraph  wire 
conducting  electricity  from  the  battery  to  the  distant 
telegraph  instrument.  In  these  connections  we  speak  of 
the  conduction  of  heat  and  of  electricity ;  but  We  receive 
heat  from  the  sun  over  a  space  of  millicms  of  miles  in 
which  there  is  nothing  to  conduct  the  heat.  As  more 
particularly  stated  in  another  chapter,  we  receive  the  heat 
from  the  sun  by  means  of  the  ether,  which  does  not  con- 
duct heat  at  all.  We  picture  the  heat  of  the  sun  setting 
up  waves  or  vibrations  in  the  ether,  which  in  turn  sets  op 
heat  on  the  earth.  We  might  say  that  the  heat  in  the 
sun  induces  heat  in  the  earth,  and  in  the  same  way  we 
find  electricity  in  one  body  inducing  electricity  in  a 
neighbouring  body  with  which  it  is  not  in  contact. 

In  speaking  of  electricity  which  has  been  thus  induced, 
we  say  it  has  been  produced  by  induction ;  and  so  by  an 

167 


INDUCTION   COIL 

induction  coil  we  mean  a  machine  by  which  a  current  of 
electricity  in  one  wire  or  coil  will  induce  a  similar  current 
in  a  second  and  separate  coil.  One  may  naturally  ask 
what  advantage  is  to  be  derived  by  doing  this.  The 
result  of  a  preliminary  experiment  seems  rather  dis- 
heartening. We  fit  up  two  coils,  connecting  one  to  a 
battery,  and  we  place  the  second  coil  near  it,  this  coil 


FIG.  10 

THE  PBINCIPLE   OF  INDUCTION   COILS 

When  the  push  (P)  is  pressed  a  current  flows  through  coil  No,  I  from 
the  battery  (B),  and  at  the  making  and  breaking  of  this  current  an 
electric  current  is  set  up  in  coil  No.  2,  which  is  quite  separate.  This 
induced  current  is  detected  by  the  galvanometer  (G). 

being  attached  to  an  instrument  for  detecting  the  flow  of 
a  current.  The  diagram  (Fig.  10)  shows  this  simple  ar- 
rangement with  a  bell-push  inserted  between  the  battery 
and  No.  1  coil,  so  that  we  may  conveniently  switch  off 
and  on  the  current  at  will. 

We  know  that  as  soon  as  we  press  the  push  a  current 
will  flow  in  No.  1  coil.  We  press  the  button,  and  watch- 
ing the  detecting  instrument  in  the  other  coil,  we  see  its 

108 


WHAT  INDUCTION  MEANS 

indicator  fall  to  one  side,  showing  that  a  current  of  elec- 
tricity has  been  set  up  in  No.  2  coil,  and  it  is  clear  that 
this  current  must  have  been  produced  by  induction  from 
the  battery  current  in  No.  1  coil,  as  there  is  no  connection 
between  the  two  coils.  Still  keeping  a  finger  on  the  push, 
we  notice  that  the  indicator  has  gone  back  to  zero,  show- 
ing that  the  current  is  no  longer  flowing  in  No.  2  coil, 
although  the  battery  current  is  still  flowing  in  No.  1. 
When  we  let  go  the  push,  we  notice  the  indicator  in  No.  2 
coil  move  once  more,  but  this  time  in  the  opposite  direc- 
tion, and  by  repeating  the  experiment  we  find  that  every 
time  we  make  or  break  the  battery  current  in  No.  1  coil  a 
momentary  current  is  set  up  in  No.  2  coil. 

There  is  the  same  amount  of  current  set  up  at  make  as 
at  break,  but  the  latter  takes  place  in  a  shorter  time,  and 
is  therefore  more  intense,  so  to  simplify  matters  we  will 
leave  the  current  produced  at  make  out  of  account  alto- 
gether. We  need  only  remember  that  each  time  we  press 
and  let  go  the  push  in  No.  1  coil  a  momentary  current  is 
set  up  in  No.  2  coil.  The  quicker  we  press  the  push  the 
more  of  these  transient  currents  do  we  set  up,  and  if  we 
could  make  them  follow  very  closely  at  each  other's  heels, 
they  would  make  practically  a  continuous  current. 

We  cannot  hope  to  operate  a  bell-push  rapidly  enough 
to  get  this  effect,  and  so  automatic  contact  breakers  are 
required.  The  induction  coil  may  be  made  to  do  this 
itself,  as  will  be  explained.  Or  the  make  and  break  may 
be  obtained  by  a  small  motor,  driven  by  a  separate  battery. 
Part  of  the  circuit  may  consist  of  a  metal  point  dipping 
into  mercury,  and  the  motor  may  raise  and  lower  the 
point  alternately,  producing  the  neeessary  make  and  break. 

169 


AN  ANALOGY 

There  are  other  methods,  but  first  of  all  we  wish  to  see 
what  advantage  an  induction  coil  is  going  to  give  us. 

We  may  imagine  No.  1  coil  sending  out  electro- 
magnetic waves  in  the  ether,  and  these  waves,  as  they 
fall  on  coil  No.  2,  setting  up  a  current  in  this  coil.  It  is 
the  changes  in  this  field  of  influence  which  give  rise  to 
the  induced  current,  for  as  long  as  the  battery  current 
keeps  up  a  steady  influence,  no  current  is  induced  in  No.  2 
coil,  but  only  when  the  waves  are  being  set  up  or  with- 
drawn does  the  current  appear  in  the  neighbouring  coil. 
The  more  of  these  waves  or  lines  of  force  we  can  entrap 
the  better  result  we  get,  and  we  find  the  effect  increased 
for  every  turn  of  wire  we  add  to  No.  2  coil,  so  we  make 
this  coil  of  very  fine  wire  in  order  to  get  a  great  many 
turns  into  the  field  of  influence.  If  we  made  the  two 
coils  exactly  alike  we  should  gain  nothing,  and  even  now 
we  cannot  hope  to  increase  the  amount  of  electricity,  but 
we  may  alter  its  condition.  We  may  think  of  the  battery 
current  in  No.  1  coil  as  an  easy-flowing  current  of  con- 
siderable volume,  while  in  No.  2  coil  we  have  a  small 
current  at  a  very  great  pressure.  It  is  difficult  to  find  any 
convenient  analogy,  but  I  think  one  may  liken  the  process 
to  that  of  a  mechanical  lever.  A  workman  wishes  to 
move  a  large  stone,  but  finds  it  too  heavy.  He  gets  a 
simple  bar  of  iron,  and  putting  one  end  under  the  stone, 
he  places  some  obstacle  under  the  bar  or  lever  near  to  the 
large  stone,  and  then  applying  his  energy  to  the  free  end 
of  the  lever,  he  finds  he  can  easily  move  the  heavy  stone. 
From  whence  did  he  get  the  increase  of  power  ?  Energy 
cannot  be  created  by  a  simple  iron  bar  or  by  any  other 
means,  but  it  is  apparent  that  the  workman  moved  the 

170 


AN   ANALOGY 

free  end  of  the  lever  through  a  far  greater  distance  than 
the  stone  was  moved,  so  that  he  merely  concentrated  his 
energy.  We  might  speak  of  the  energy  he  put  into 
several  feet  of  movement  being  concentrated  into  several 
inches,  and  this  may  serve  as  a  rough  analogy  of  what  an 
induction  coil  does :  it  cannot  increase  the  energy,  but  it 
concentrates  it,  and  we  have  a  very  high  voltage  or  pres- 
sure, sometimes  reaching  over  a  million  volts.  A  single 
battery  cell  gives  a  pressure  of  from  one  to  two  volts. 

When  the  principle  of  an  induction  coil  is  once  grasped, 
the  construction  is  readily  understood.  No.  1  coil,  which 
is  the  battery  circuit,  is  called  the  primary  coil  or  circuit, 
while  the  coil  in  which  the  current  is  to  be  induced  is 
called  the  secondary  circuit.  The  electro-magnetic  effect 
of  the  primary  coil  is  increased  about  thirty  fold,  by  placing 
a  piece  of  iron  inside  the  coil.  A  bundle  of  iron  wires  is 
used,  as  they  magnetise  and  demagnetise  quicker  than 
a  solid  piece  of  iron  does.  The  battery  or  primary  circuit 
is  wound  around  this  bundle  of  wires,  the  coil  being,  of 
course,  carefully  insulated,  or  otherwise  the  current  will 
not  go  round  and  round  the  coil  as  is  desired.  One  may 
always  think  of  the  insulation  being  to  the  current  what 
a  pipe  is  to  water  or  gas.  The  two  ends  of  this  primary 
coil  are  connected  to  the  battery,  there  being  a  contact 
breaker  inserted  between  one  end  and  the  battery,  as  was 
represented  in  the  diagram  (Fig.  10)  by  the  bell-push. 
The  secondary  coil  of  very  fine  wire  is  wound  directly  on 
the  top  of  the  primary  coil,  but  very  carefully  insulated 
from  it,  and  its  two  ends  are  left  free,  being  merely  finished 
off  in  convenient  terminals,  so  that  any  desired  piece  of 
apparatus  may  be  connected  in  circuit  with  this  coiL 

171 


MODERN  IMPROVEMENTS 

As  already  indicated,  the  contact  breaker  may  be 
worked  by  the  induction  coil  itself,  for  the  bundle  of  iron 
wires,  becoming  a  magnet  whenever  the  battery  current 
flows  round  them,  may  be  made  to  attract  a  piece  of  iron 
attached  to  a  spring,  which,  when  attracted  forward, 
breaks  the  path  of  the  current  from  the  battery. 

Immediately  the  circuit  is  broken  the  bundle  of  iron 
wires  lets  go  the  spring  piece,  which,  coming  once  more  to 
its  normal  position,  allows  the  current  again  to  pass, 
whereupon  the  spring  is  again  attracted  forward,  and  so 
the  make  and  break  is  kept  up  continuously.  The  motion 
is  exactly  that  of  the  gong-stick  in  an  ordinary  electric 
bell,  and  it  is  the  rapid  to-and-fro  movement  of  this 
spring  that  causes  the  monotonous  hum  in  the  air  when 
an  induction  coil  is  at  work. 

The  breaking  of  the  battery  circuit  might  be  accom- 
plished by  turning  a  wheel  round,  having  contact  pieces 
at  intervals  on  its  periphery,  and  indeed  this  method  was 
employed  prior  to  the  automatic  arrangement  just 
described.  One  modern  method  is  to  give  a  rapid  motion 
to  a  contact  lever  by  means  of  a  small  motor  driven  by 
electricity.  There  are  also  electrolytic  contact  breakers 
now  in  use,  but  the  object  of  all  is  merely  to  obtain 
a  rapid  make  and  break  of  the  battery  circuit.  The  only 
other  point  to  mention  is  that  a  condenser,  made  up  of 
insulated  layers  of  metal  foil,  is  placed  in  the  wooden 
base  of  the  instrument,  to  act  as  a  Ley  den  jar.  The 
induction  coil  is  also  supplied  with  a  switch,  to  turn  off 
and  on  the  battery  current  at  will,  and  also  a  commutator 
switch,  so  that  the  direction  of  the  current  may  be  re- 
versed. 

172 


MODERN   IMPROVEMENTS 

If  a  glass  tube,  from  which  the  air  has  been  as  effectively 
withdrawn  as  possible,  be  now  coupled  to  the  induction 
coil,  a  beautifully  luminous  effect  is  produced  in  the 
tube.  This  phenomenon  has  led  up  to  some  most  im- 
portant uses  of  the  induction  coil,  which  will  be  dealt 
with  in  the  following  chapter  under  the  title  of  "  Light 
that  does  not  Affect  the  Eye." 


173 


CHAPTER  XVII 

LIGHT  THAT  DOES  NOT  AFFECT 
THE  EYE 

All  light  is  of  itself  invisible— Early  observations  leading  up  to  the 
discovery  of  the  "  X-rays  "—How  we  are  able  to  see  the  living 
skeleton— The  means  by  which  invisible  rays  are  made  visible — 
How  the  X-rays  are  produced— Some  applications  of  the  Rontgen 
rays. 

THE  title  of  this  chapter  may  appear  rather  clumsy, 
but  the  expression  "light  visible  and  invisible," 
which  is  so  much  in  use  at  present,  has  always 
seemed  to  me  misleading.  I  remember  how,  when  quite 
a  youngster,  I  was  very  much  impressed  by  the  fact  that 
all  light  must  be  invisible.  Walking  along  one  night  in 
the  dark  I  pictured  the  sun  at  the  other  side  of  this  great 
globe,  but  sending  his  rays  of  light  away  out  into  space, 
reaching  to  the  other  planets.  It  was  quite  apparent 
then  that  light  must  be  invisible,  or  we  should  see  these 
rays  of  light  beyond  the  shadow  of  the  earth,  and  so  I 
was  impressed  by  the  fact  that  all  light  is  invisible  before 
I  came  to  learn  the  scientific  explanation  of  the  matter. 
As  already  pointed  out,  it  is  really  a  necessity  that  we 
should  have  a  new  word  to  denote  light  as  an  ether  dis- 
turbance, so  that  it  may  not  be  confounded  with  light 
sensation  in  the  material  retina  and  optic  nerve. 

We  have  a  great  variety  of  ether  waves,  as  explained 


Ky  permission  Of  Glasgow  Corporation  Telephone  Department. 

SHANGHAI    TELEPHONE    EXCHANGE 

In  the  Telephone  Exchange  at  Shanghai  the  operators  are  Chinese  boys,  who  have 
proved  very  efficient  workers.  The  details  of  the  switchboard  ars  clearly  seen,  as 
described  in  Chapter  XIV. 


DISCOVERY  OF  X-RAYS 

in  a  later  chapter.  Only  a  very  small  proportion  of 
these  waves  affect  our  eyes.  But  while  the  retina  is 
not  disturbed  by  some  rays  of  light,  these  affect  the 
chemical  preparation  on  a  photographic  plate.  We  are 
all  now  quite  familiar  with  the  so-called  "  shadowgraphs  " 
produced  by  the  Rontgen  rays,  or  as  Professor  Rontgen 
named  them  "  the  X-rays,"  which  reminds  one  of  algebra, 
"let  x  be  the  unknown  quantity."  By  the  way,  those 
who  have  examined  such  photographs  carefully  must 
have  noticed  that  they  are  not  merely  shadows,  but  that 
there  is  a  great  variety  of  density,  and  that  there  is  no 
flatness  as  in  a  shadow,  but  the  objects  are  rounded  off 
like  solid  bodies. 

When  in  1896  it  was  announced  that  the  living  skeleton 
could  not  only  be  photographed,  but  might  be  plainly 
seen  upon  a  screen,  and  the  movements  of  every  bone 
watched,  the  whole  civilised  world  was  at  once  interested. 
There  was  a  sort  of  fascinating  eeriness  about  the  subject 
which  doubtless  gave  it  a  wider  interest  than  scientific 
discoveries  usually  produce. 

It  will  be  of  some  interest  to  see  how  this  very  import- 
ant discovery  came  about.  There  must  have  been  a  great 
number  of  observed  facts  leading  up  to  this,  for  even  the 
greatest  scientists  do  not  stumble  across  discoveries  unless 
they  are  making  their  way  along  some  definite  path  in 
which  this  previously  unobserved  phenomenon  lies.  The 
now  famous  German  professor  did  not  invent  the  Rontgen 
rays;  they  had  been  present  in  many  experiments  for  a 
long  time  back,  but  had  not  been  observed. 

In  the  primitive  electrical  machines,  in  which  the  ether 
disturbance  was  produced  by  the  experimenter  holding  his 

'75 


LUMINOUS  EFFECTS 

hand  against  a  revolving  glass  cylinder  or  globe,  it  had 
been  noticed  that  if  the  air  was  withdrawn  from  the 
globe  by  means  of  an  air-pump,  a  beautiful  glow  of  light 
appeared  inside  the  globe  when  it  was  excited  by  rubbing 
against  the  hand.  This  luminous  effect  was  not  present 
unless  the  globe  was  approximately  a  vacuum.  This  was 
known  some  one  hundred  and  seventy  years  ago ;  and 
about  that  time  it  occurred  to  one  experimenter  to  try  if 
this  luminous  effect  could  be  produced  in  the  vacuum 
globe  by  electrifying  it  from  another  machine  instead  of 
exciting  the  globe  directly  by  the  hand.  The  Polish 
scientist  who  tried  this  was  delighted  to  find  that  when  he 
passed  a  charge  of  electricity  from  one  of  these  primitive 
machines  through  a  vacuum  tube  the  luminous  effect 
appeared,  and  he  at  once  proposed  to  use  this  light  in 
mines  and  places  where  an  ordinary  light  was  dangerous. 
If  this  method  of  lighting  had  been  tried  in  any  dangerous 
mine,  I  fear  the  consequences  might  have  been  serious,  for 
it  would  have  been  very  difficult  to  prevent  sparks  passing 
from  the  highly  charged  wires,  and  these  sparks  would 
be  quite  sufficient  to  cause  ignition  of  gases  followed  by 
explosion.  However,  we  find  that  for  more  than  a  century 
and  a  half  this  light  produced  by  an  electrical  discharge 
in  a  vacuum  has  been  known  to  scientists  and  to  those 
interested  in  such  matters. 

When  a  discharge  passes  between  two  points  in  ordi- 
nary air,  producing  a  spark,  the  air  offers  a  great  deal  of 
resistance  to  the  electricity,  and  the  disturbance  caused 
by  the  discharge  is  of  quite  a  violent  nature.  The  same, 
of  course,  holds  good  if  the  discharge  takes  place  inside 
a  tube  filled  with  air ;  but  if  we  connect  the  tube  to  an 

176 


ARTIFICIAL  AURORA 

air-pump  and  commence  to  withdraw  the  air,  we  soon  find 
that  there  is  not  the  same  resistance  to  the  electrical  dis- 
charge, and  that  we  are  able  to  place  the  two  points  much 
farther  apart  and  still  get  a  discharge.  As  the  air  in  the 
tube  becomes  less  we  find  the  discharge  becoming  quite 
silent,  and  instead  of  repeated  sparks  there  is  a  constant 
stream  of  luminosity. 

Even  when  we  have  got  the  very  best  vacuum  that  is 
possible,  we  must  not  imagine  that  there  are  no  mole- 
cules of  air  left  in  the  tube,  for  it  can  very  easily  be 
proved  that  the  light  is  dependent  upon  some  particles 
of  air  remaining.  If  the  tube  be  filled  with  any  other 
gas,  such  as  hydrogen,  and  the  pump  made  to  withdraw 
all  the  gas  it  can,  the  discharge  in  the  so-called  vacuum 
remaining  is  quite  different  in  appearance  from  that 
which  took  place  after  the  ordinary  air  had  been  with- 
drawn from  the  tube.  There  is  now  a  blue  glow  with  a 
crimson  effect  in  the  centre,  and  if  the  tube  has  been 
filled  with  a  mixture  of  gases  before  the  pump  is  applied, 
the  effect  of  an  aurora  borealis  on  a  small  scale  may  be 
produced. 

It  is  therefore  evident  that  the  luminous  effect  is  pro- 
duced by  the  particles  of  air  or  gas  left  in  the  "  vacuum," 
and  we  may  imagine  these  remaining  molecules  to  be 
bombarded  about  by  the  discharge  so  rapidly  in  the 
free  space  now  at  their  disposal  that  they  become 
luminous. 

With  improvements  hi  air-pumps  it  was  possible  to 
produce  more  rarefied  vacuums,  and  we  are  indebted  to 
our  great  English  chemist,  Sir  William  Crookes,  for  much 
M  177 


HOW  X-RAYS  ARE  PRODUCED 

progress  in  this  branch  of  science.  Crookes  produced 
tubes  with  such  high  vacua  that  the  diffused  luminosity 
or  glow  concentrated  itself  into  a  direct  stream  between 
the  two  conducting  points  as  though  it  were  a  luminous 
thread,  and  he  found  that  a  magnet  held  near  the  tube 
would  deflect  this  stream  from  its  direct  path.  It  was 
also  observed  that,  when  these  rays  fell  upon  the  glass  of 
the  tube,  they  made  it  glow  with  a  green  or  bluish  phos- 
phorescence. These  rays  are  now  famous  in  the  scientific 
world,  and  are  called  "  cathode  rays."  Before  these  rays 
become  observable,  the  air  in  the  tube  must  be  as  greatly 
rarefied  as  it  is  away  up  about  one  hundred  miles  above 
the  surface  of  the  earth. 

While  Professor  Rontgen,  of  Wiirzburg,  was  work- 
ing with  some  of  these  high-vacuum  tubes  he  found 
that  there  were  other  rays  originating  from  the  point 
where  these  cathode  rays  impinged  upon  the  glass  or 
upon  any  other  obstruction.  By  further  experiment  he 
found  that  these  unknown  or  X-rays  would  pass  through 
a  great  many  bodies  which  were  quite  opaque  to  ordinary 
light.  Other  substances  were  able  to  stop  the  rays,  and 
when  caused  to  fall  on  a  photographic  plate  they  set  up 
the  same  chemical  action  as  ordinary  light,  producing  a 
negative  in  the  usual  way  when  developed.  Rontgen  thus 
showed  that  a  photograph  of  the  bones  of  the  hand  might 
be  taken  if  the  hand  was  interposed  between  the  tube  and 
the  photographic  plate, 

We  shall  see  in  the  following  chapter  the  very  great 
boon  that  this  discovery  has  been  to  suffering  man. 

Crookes  had  already  shown  that  if  he  caused  the 

178 


HOW  X-RAYS  ARE  PRODUCED 

cathode  rays  to  fall  upon  different  crystals,  by  placing 
them  in  the  path  of  the  cathode  stream,  the  crystals 
became  phosphorescent  or  fluorescent.  It  had  also  been 
observed  that  if  a  piece  of  glass,  coloured  greenish  by 
uranium,  were  moved  along  in  the  spectrum  produced  by 
light  passing  through  a  prism,  the  glass  reflected  the 
colours  as  ordinary  glass  would  do,  but  when  moved  along 
beyond  the  visible  spectrum  at  the  violet  end  the  glass 
still  showed  the  green  tint,  although  there  was  no 
apparent  light  falling  upon  it.  That  is  to  say,  there 
were  light  waves  which  did  not  directly  affect  the  eye,  but 
which  were  changed  by  striking  upon  the  uranium  glass 
and  then  became  visible. 

When  the  sun's  rays  pass  through  a  glass  prism  the 
different  wave  lengths  are  separated  and  fall  upon  the 
floor  or  wall  in  a  band  of  beautiful  rainbow  colouring, 
with  the  appearance  of  which  we  are  all  familiar.  At 
one  time  it  would  have  seemed  ridiculous  to  suggest  that 
there  was  anything  more  than  the  visible  spectrum,  but 
now  we  know  that  there  are  rays  beyond  this  limit  in 
both  directions,  although  the  eye  does  not  detect  them. 
Those  beyond  the  violet  end  of  the  spectrum  will  affect  a 
photographic  plate,  while  some  will  even  illuminate  a 
fluorescent  screen.  In  the  other  direction,  beyond  the  red 
end  of  the  spectrum,  we  find  the  rays  or  ether  waves 
which  affect  the  wireless  telegraph  receiver. 

A  fluorescent  screen  such  as  used  in  X-ray  work  is 
merely  a  cardboard  coated  with  some  fine  crystals,  such  as 
platino-cyanide  of  barium.  The  ether  waves  striking 
upon  these  crystals  are  so  altered  that  they  are  brought 

179 


HOW   X-RAYS   ARE  PRODUCED 

within  the  scope  of  our  vision.  In  other  words,  when  the 
invisible  X-rays  fall  upon  the  crystals  they  cause  these 
to  send  out  ether  waves  which  do  affect  our  eyes.  The 
illumination  of  the  screen  lasts  only  so  long  as  the  X-rays 
continue  to  impinge  upon  the  crystals.  There  are  other 
phosphorescent  substances  which  continue  to  emit  light 
after  the  stimulating  waves  have  been  withdrawn. 

When  the  X-rays  fall  upon  a  fluorescent  screen  they 
illuminate  it  evenly  all  over  provided  there  is  no  obstacle 
between  the  tube  and  the  screen  to  intercept  the  X-rays. 
If  the  hand  be  held  between  the  tube  and  the  screen,  a 
shadowgraph  or  radiograph  is  produced  upon  the  lumin- 
ous screen. 

The  principle  of  the  X-ray  tube  will  be  understood 
from  the  diagram  on  page  181.  The  cathode  rays  im- 
pinge upon  the  little  sloping  target,  and  this  bombard- 
ment sets  up  the  ether  disturbance  known  as  X-rays. 

When  we  come  to  consider  the  nature  of  electric 
phenomena  we  shall  see  that  the  so-called  cathode  rays 
are  composed  of  very  small  particles  which  cannot  escape 
through  the  glass,  whereas  the  X-rays,  being  merely  an 
ether  disturbance,  can  pass  out  through  the  glass  of  the 
tube.  We  are  not  sure  of  the  nature  of  the  X-rays, 
further  than  that  they  are  a  disturbance  in  the  ether, 
possibly  a  series  of  splashes  or  thin  pulses. 

The  value  of  the  X-rays  to  us,  as  far  as  photography 
is  concerned,  is  due  to  the  fact  that  they  can  penetrate 
many  substances  which  are  opaque  to  light.  The  X-rays 
have  little  difficulty  in  passing  through  a  wooden  box. 
They  penetrate  the  flesh  of  the  hand  with  ease,  but  have 
their  way  blocked  by  the  bones  of  the  fingers. 

180 


APPLICATION  OF  THE  RAYS 

There  are  other  applications,  such  as  the  detection  of 
imitation  gems.  A  real  diamond  is  quite  transparent  to 
the  rays,  while  imitation  ones  are  practically  opaque. 
The  X-rays  have  been  used  also  in  testing  the  manufac- 
ture of  electric  cables.  By  passing  the  cable  between  an 
X-ray  tube  and  a  fluorescent  screen,  the  inside  of  the 


FIG.  11 

AN    X-UAY   TUBE 

This  diagram  represents  a  simple  form  of  X-ray  tube.  The  cathode 
rays  pass  from  the  cathode  (  -  )  to  the  anode  ( + ).  They  are  focussed  by 
the  saucer-shaped  cathode  so  that  they  strike  the  target,  which  is  seen 
lying  at  an  angle.  When  the  cathode  rays  are  stopped  suddenly  by  the 
target,  they  produce  a  sort  of  splash  in  the  ether,  as  indicated  by  the 
dotted  lines.  This  ether  disturbance  is  what  we  call  the  X-rays. 

cable  insulation  may  be  examined  and  faults  located. 
The  presence  of  foreign  bodies  in  the  insulating  material 
is  easily  detected.  The  X-rays  have  also  been  of  great 
value  to  the  scientist,  but  their  practical  application  in 
the  medical  world  far  surpasses  any  other  application 
likely  to  be  made. 

181 


CHAPTER  XVIII 

HOW  ELECTRICITY  PRODUCES 
LIGHT 

The  first  idea  of  an  electric  light— Discovery  of  the  electric  arc— 
What  happens  in  an  arc-lamp — How  we  came  to  have  incandescent 
lamps— The  true  meaning  of  combustion— Edison's  first  idea  for 
a  glow-lamp — A  common  error  in  comparing  gas  and  electric  light- 
ing—An interesting  old  lady — Artificial  daylight. 

IT  would  be  difficult  to  say  when  the  very  first  thought 
of  an  electric  light  entered  the  mind  of  man,  for 
such  an  idea  might  even  have  been  suggested  in  some 
way  to  the  philosophers  of  many  ages  ago*     It  is  re- 
corded that  one  ancient  philosopher  had  observed  sparks 
emitted  by  his  stockings  while  in  the  act  of  undressing, 
and  in  these  tiny  sparks  we  see  some  connection  between 
electricity  and  light. 

Early  experimenters  must  have  been  more  impressed 
with  this  connection  when  the  primitive  frictional  machines 
came  into  use,  for  in  the  dark  some  beautifully  luminous 
effects  were  produced.  It  is  not  probable,  however, 
that  these  distant  workers  ever  dreamed  of  a  practical 
electric  light. 

Early  in  the  nineteenth  century  that  very  thoughtful 
Cornish  experimenter,  Sir  Humphry  Davy,  made  an  im- 
portant discovery.  Having  coupled  together  the  whole 

182 


THE  ELECTRIC  ARC 

of  his  battery  of  two  thousand  cells,  he  connected  a 
carbon  pencil  to  each  of  the  two  battery  wires,  where- 
upon he  found  that  if  the  carbons  were  made  to  touch 
each  other,  thus  completing  the  circuit,  and  if  then 
gradually  separated,  the  spark  between  them  became  a 
very  brilliant  continuous  arch  or  "arc"  of  light.  Not 
only  do  the  carbon  points  become  white-hot,  but  a  con- 
tinuous stream  of  volatilised  particles  fills  the  intervening 
space.  The  carbons  gradually  waste  away,  but  it  will  be 
understood  that  the  heat  and  light  are  in  no  way  de- 
pendent upon  combustion.  The  arc  is  maintained  by  the 
electric  current,  which  is  necessarily  at  a  high  pressure 
to  overcome  the  great  resistance  offered  to  its  passage 
across  between  the  carbon  points. 

The  arc-lamp,  with  which  we  are  all  familiar  in  our 
streets,  railway  stations,  or  public  buildings,  is  nothing 
more  than  a  machine  to  feed  the  carbons  forward  as 
required,  and  to  start  or  "  strike "  the  arc.  Unless  the 
carbons  are  put  in  contact  with  each  other  to  start  with, 
the  current  cannot  get  across  from  the  one  to  the  other,  but 
when  the  current  is  turned  on  the  carbons  are  in  contact 
with  each  other,  and  as  soon  as  the  current  passes  the 
lamp  automatically  separates  the  carbon  points  and  thus 
forms  the  arc. 

An  arc-lamp  placed  in  the  focus  of  a  large  reflector 
in  a  lighthouse  tower  may  be  visible  for  at  least  twenty 
or  thirty  miles  on  a  clear  night,  and  indeed  very  powerful 
lamps  equal  to  hundreds  of  thousands  of  candles  may 
be  discerned  at  a  distance  of  over  one  hundred  miles. 
Quite  recently  a  flash-light  has  been  put  into  St.  Catherine's 
Lighthouse  in  the  Isle  of  Wight,  which  is  estimated  at 

183 


WHAT  HAPPENS   IN   AN   ARC-LAMP 

fifteen  million  candle  power,  and  which  should  be  seen 
from  the  French  coast  in  clear  weather. 

In  connection  with  the  arc-lamp  it  is  interesting  to 
note  that  no  matter  how  close  the  carbon  points  are 
brought  to  each  other  at  the  outset  no  current  will  pass 
until  they  actually  touch ;  then  they  quickly  become 
heated,  and  when  separated  a  bridge  of  carbon  vapour  is 
formed  between  them.  If  an  arc-lamp  "  hisses  "  then  one 
knows  that  the  carbon  points  are  not  far  enough  separated, 
or  if  there  is  a  flashing  and  spluttering  the  distance  is  too 
great,  but  an  up-to-date  arc-lamp  works  very  steadily 
indeed. 

An  arc-lamp  was  used  in  1858,  when  the  foundations  of 
Westminster  Bridge  across  the  Thames  were  being  laid, 
but  while  this  is  sometimes  quoted  as  the  first  time  that 
an  electric  light  was  used  for  a  practical  purpose  it  is  not 
really  so,  as  the  Parisians,  some  eleven  years  earlier, 
illuminated  the  Place  de  la  Concorde  by  means  of  an  arc- 
lamp. 

In  the  arc-lamp  it  is,  of  course,  necessary  to  replace  the 
carbon-sticks  or  pencils  continually,  owing  to  their  wasting 
away  as  already  mentioned,  but  of  late  years  many  arc- 
lamps  have  been  made  in  which  the  carbons  are  enclosed 
in  a  globe  into  which  the  air  leaks  but  slowly,  thus  pre- 
venting the  carbons  wasting  away  so  rapidly.  While  the 
carbons  in  an  ordinary  open  arc  do  not  last  more  than 
twelve  to  sixteen  hours,  an  enclosed  arc-lamp  may  burn 
for  a  hundred  and  fifty  hours  before  requiring  new  carbons, 
which  means  a  considerable  saving,  not  only  in  carbons, 
but  also  in  the  work  of  attending  to  the  lamps. 

We  have  seen  that  Sir  Humphry  Davy  was  the  first  to 

184 


MEANING  OF  COMBUSTION 

produce  the  electric  arc  giving  us  the  basis  of  arc-lighting, 
and  as  the  same  ingenious  experimenter  showed  that  a 
continuous  stick  of  carbon  could  be  made  white-hot  by 
passing  sufficient  current  through  it,  he  has  at  least  given 
the  suggestion  of  another  method  of  lighting.  No  doubt 
Davy's  mind  would  be  absorbed  with  the  heating  property 
of  the  arc,  as  that  would  appeal  to  him  strongly,  he  being 
a  great  chemist,  but  this  will  be  dealt  with  later  in  the 
chapter  on  "  Electricity  as  a  Heating  Agent." 

If  a  wire  or  thread  of  carbon  is  made  white-hot  by 
passing  a  current  through  it,  the  carbon  will  very  soon 
disappear  owing  to  combustion,  and  it  was  the  prevention 
of  this  waste  that  made  electric  lighting  by  means  of  a 
carbon  wire  possible.  Some  people  find  it  difficult  to  see 
quite  clearly  how  it  is  that  electric  light  has  to  take  the 
fact  of  combustion  into  account  and  yet  that  it  is  in  no 
way  produced  by  combustion.  I  think  this  matter  may 
be  explained  by  a  very  simple  and  well-known  experiment. 
If  a  lighted  candle  is  placed  inside  a  large  glass  bottle  and 
its  mouth  closed,  the  candle  burns  for  a  little  time,  but 
its  light  soon  becomes  fainter  and  fainter  and  then  dis- 
appears. A  second  lighted  candle  lowered  into  the  bottle 
will  now  immediately  go  out.  The  reason  for  this  result 
is  no  doubt  plain  to  all.  The  bottle  at  the  outset  con- 
tained a  certain  amount  of  air  dependent  entirely  upon 
its  capacity,  and  when  the  lighted  candle  was  put  in  the 
bottle  was  corked  so  that  no  air  could  escape  or  enter. 
No  air  has  passed  out  of  the  bottle,  and  yet  the  candle 
will  not  burn.  It  is,  therefore,  evident  that  the  condition 
of  the  air  must  now  be  quite  different.  There  has  been  a 
chemical  change  going  on :  the  carbon  in  the  candle  when 

185 


MEANING  OF  COMBUSTION 

heated  has  been  able  to  unite  with  the  oxygen  of  the  air, 
and  has  thus  formed  carbon  dioxide,  commonly  called 
carbonic  acid  gas.  The  chemist  signifies  this  by  the 
symbol  CO2,  which  reads  that  a  molecule  of  this  new 
compound  is  composed  of  one  part  of  carbon  and  two 
parts  of  oxygen.  In  chemistry  each  element  has  a  dis- 
tinctive and  easily  remembered  symbol  as  C  for  carbon, 
O  for  oxygen,  H  for  hydrogen,  Cu  for  Copper,  Zn  for 
zinc,  and  so  on.  The  chemical  symbol  for  water  will 
therefore  be  H2O,  a  water  molecule  being  a  combination 
of  two  parts  of  hydrogen  with  one  of  oxygen. 

To  return  to  the  bottle  with  the  extinguished  candle, 
it  becomes  apparent  that  the  uniting  of  the  carbon  of  the 
candle  and  the  oxygen  of  the  air  has  ceased,  and  as  a 
good  deal  of  the  candle  remains  and  can  be  relighted 
outside  of  the  bottle,  it  is  evident  that  all  the  oxygen 
of  the  bottle-full  of  air  has  united  with  the  candle's  carbon, 
so  that  no  further  chemical  union  can  go  on.  To  this 
act  of  chemical  combination  we  give  the  simple  name  of 
"  combustion,"  and  in  the  case  of  the  lighted  candle, 
when  we  keep  it  well  supplied  with  oxygen,  as  we  do  in 
burning  it  in  the  open  air,  the  combustion  will  go  on  as 
long  as  there  is  any  candle  left.  It  is  this  combustion 
that  causes  the  candle  to  give  heat  and  light,  for  the 
minute  particles  of  carbon  become  white-hot  and  luminous. 
We  must  have  the  combustion  and  consequent  change  of 
material  to  have  the  lighted  candle,  for  if  we  prevent  the 
combustion  by  taking  away  all  the  available  oxygen,  we, 
of  course,  get  no  chemical  union,  and,  therefore,  no  light. 
But  if  we  can  raise  and  maintain  a  white  heat  by  some 
other  means  than  combustion  then  the  conditions  are 
quite  different. 

186 


FIRST  IDEA  FOR  A  GLOW-LAMP 

It  was  known  from  the  outset  that  a  current  of 
electricity  heated  the  'Conductor  through  which  it  was 
flowing,  and  the  greater  the  resistance  offered  to  the 
current  the  greater  the  heat.  Sir  Humphry  Davy 
showed  a  wire  of  carbon  raised  to  a  white  heat  by  the 
passage  of  an  electric  current,  so  all  that  remained  to 
be  done  was  to  prevent  any  oxygen  getting  near  the 
heated  carbon.  It  is  from  the  air  that  the  carbon  steals 
the  oxygen,  so  our  best  plan  is  to  keep  the  carbon  out 
of  the  way  of  temptation  by  shutting  it  up  where  it 
cannot  get  a  hold  of  any  air.  This  is  easily  accomplished 
by  sealing  up  the  carbon  in  a  glass  globe  after  exhausting 
all  the  air  from  it  by  means  of  an  air-pump.  The  carbon 
may  now  be  raised  to  a  white  heat  by  the  current  and 
made  to  glow,  but  combustion  is  prohibited,  and,  there- 
fore, there  is  no  appreciable  waste.  Some  tiny  particles 
of  carbon  do  manage  to  free  themselves  from  the  carbon 
"  filament,1"  as  may  be  seen  in  a  lamp  that  has  been  long 
in  use,  by  a  blackening  of  the  inside  of  the  globe. 

These  glow-lamps  are  descriptively  named  electric 
incandescent  lamps.  The  carbon  filament  in  one  of  these 
lamps  is  very  fine,  so  that  it  offers  a  very  poor  passage 
to  the  current,  and,  therefore,  is  more  easily  heated, 
whereas  the  metal  wires  leading  to  the  lamp  and  into 
the  carbon  are  much  better  conductors,  and  allow  the 
current  so  free  a  passage  that  the  heating  of  them  is  quite 
inappreciable.  The  temperature  of  the  little  carbon 
filament  is  somewhere  about  3,450°  on  Fahrenheit's  scale. 

Although  Sir  Humphry  Davy's  carbon  stick  became 
heated  by  the  passage  of  the  current,  it  did  not  at  first 
seem  possible  to  use  carbon  in  any  suitable  form  for 

187 


FIRST  IDEA   FOR  A   GLOW-LAMP 

a  small  lamp,  so  the  early  experiments  were  all  made 
with  very  fine  metal  wires  of  different  alloys.  The  great 
difficulty,  however,  was  that  when  a  fine  metal  wire 
became  white-hot  and  gave  light  it  was  very  apt  to 
fuse.  One  might  picture  this  result  as  due  to  the  mole- 
cules while  clinging  together  by  their  natural  cohesive 
force  reaching  such  a  rapid  rate  of  vibration  that  they 
are  no  longer  able  to  hold  on  to  each  other,  and  so  the 
wire  gives  way,  the  metal  tending  to  change  into  liquid 
form. 

There  is  not  this  trouble  with  carbon,  and  after  finding 
metals  unreliable  Edison  made  a  suitable  carbon  wire  by 
cutting  thin  slips  of  bamboo  grass  and  charring  them, 
while  another  practical  filament  was  made  by  Swan  by 
carbonising  a  linen  fibre  with  sulphuric  acid.* 

The  appearance  of  an  ordinary  glow-lamp  is  familiar 
to  all,  and  while  the  filament  looks  quite  substantial 
when  the  lamp  is  glowing,  it  will  be  found  to  be  a  very 
fine  thread  of  carbon  if  examined  while  the  current  is 
not  passing.  This  apparent  difference  in  size  is  merely 
an  optical  illusion  due  to  the  intense  light  from  the  white- 
hot  carbon  impinging  with  considerable  force  upon  the 
retina  of  the  eye,  and  causing,  as  it  were,  a  spreading  of 
the  sensation  to  more  of  the  retina  than  the  directly 
affected  part,  thus  conveying  the  idea  of  a  larger  image. 
This  effect  is  known  as  "irradiation,*"  and  may  be  observed 

*  In  modern  manufacture  the  materials  for  making  the  lamp  fila- 
ments are  dissolved  into  a  solution  having  a  consistency  similar  to  that 
of  treacle.  This  semi-liquid  is  then  forced  through  small  tubes,  coming 
out  as  a  continuous  thread  or  wire,  which  is  then  placed  on  carbon 
moulds  of  any  desired  shape,  and  thereafter  placed  in  a  furnace  and 
carbonised. 

iSS 


Photo.]  [W.  Stacey,  Dunmow. 

The  Son  of  the  Countess  of  Warwick  in  his  little  Electric  Motor  Car. 


GAS  AND  ELECTRIC  LIGHTING 

not  only  with  brightly  luminous  objects,  but  even  between 
black  and  white  bodies.  A  very  stout  person  looks 
stouter  when  dressed  in  white  than  when  in  black,  and 
so  on. 

These  glow-lamps  have  certain  advantages  over  gas  or 
other  artificial  illuminants,  and  not  least  of  these  is  the 
fact  that  they  do  not  steal  any  of  the  oxygen  of  the  air, 
which  we  ourselves  require  to  inhale  in  order  to  keep  up 
the  combustion  in  our  bodies.  Unless  sufficient  oxygen 
can,  by  means  of  our  sponge-like  lungs,  be  brought  within 
reach  of  our  vitiated  blood  with  which  it  unites,  we  soon 
feel  a  difficulty  in  breathing  and  a  lack  of  energy,  which, 
as  we  are  well  aware,  if  carried  to  excess  will  mean  a 
complete  cessation  of  our  vitality.  Each  ordinary  gas 
light  steals  as  much  oxygen  as  several  able-bodied  men, 
so  that  it  is  very  necessary  to  keep  a  room,  which  is 
illuminated  by  gas,  well  ventilated,  and  indeed  we  too 
often  forget  that  we  ourselves  are  incessantly  demolishing 
the  beneficial  oxygen  in  the  air  of  a  room,  and  that  it  is, 
therefore,  of  much  importance  that  at  all  times  there 
should  be  a  plentiful  supply  of  fresh  air. 

The  chemical  products  of  a  gas  light  soon  tarnish  and 
dirty  the  decorations  of  a  room,  so  that  the  electric  glow- 
lamp  has  a  distinct  advantage  in  this  respect. 

Without  discussing  the  matter  of  comparative  cost,  it 
may  be  mentioned  that  some  consumers  having  possibly 
read  comparative  statements  of  the  cost  per  candle-power 
between  gas  and  electricity  are  surprised  to  find  their 
electric  bill  considerably  higher  than  their  former  gas 
bill,  but  they  will  find  the  reason  to  be  that  they  are 
using  far  more  candle-power  than  they  formerly  did, 

189 


AN   INTERESTING   OLD  LADY 

They  would  not  be  content  to  light  a  room  electrically 
with  the  same  candle-power  as  they  previously  used  with 
gas,  for  the  glow-lamp  does  not  emit  such  a  penetrating 
light,  and  if  only  the  same  candle-power  were  provided 
the  room  would  appear  to  have  a  much  poorer  light. 

In  addition  to  the  great  convenience  of  electric  light 
and  the  advantage  of  its  leaving  our  life-sustaining 
oxygen  alone,  it  is  less  heating,  which  for  some  purposes 
is  an  advantage.  There  is  practically  no  risk  of  fire 
from  glow-lamps  if  installed  by  expert  workmen. 

It  may  be  noted  in  passing  that  in  the  electric  arc- 
lamp  the  carbons,  being  exposed  to  the  air,  are  subject 
to  combustion,  but  this  is  merely  an  effect  and  not  the 
cause  of  the  light,  as  already  explained. 

I  remember  an  old  lady,  who  had  been  bed-ridden  for 
some  twenty  years,  having  met  with  an  accident  at  the 
age  of  seventy-two,  but  retaining  clear  mental  faculties 
up  to  the  time  of  her  death  at  the  age  of  ninety-two  or 
ninety-three.  It  was  most  interesting  to  find  what  ideas 
this  old  lady  had  formed  about  this  "  electricity ,"  which 
she  had  never  seen  at  work,  nor  heard  or  read  about 
further  than  from  general  remarks  in  the  daily  news- 
papers. She  asked  many  interesting  questions,  and  in 
connection  with  electric  light,  which  she  had  never  seen  in 
any  form,  she  wanted  to  know  if  the  electricity  burned 
in  the  lamp  like  gas  or  oil.  It  was  quite  a  natural  and  a 
thoughtful  question,  and  it  is  doubtful  if  a  great  many 
people,  who  are  quite  accustomed  to  the  use  of  electric 
light,  ever  realise  this  point  that  while  gas  and  oil  are 
consumed  in  burning,  in  the  sense  of  combustion  as 
already  indicated,  it  is  quite  different  with  electricity,  as 

190 


METALLIC   FILAMENT  LAMPS 

it  merely  does  its  work  and  passes  on.  It  is  something 
like  a  river  one  sees  guided  to  a  waterwlieel,  and  after 
turning  the  mill  passing  on  its  way  as  before  to  its  great 
reservoir,  the  sea. 

In  the  case  of  the  river  we  know  that  the  sun  has 
evaporated  some  water  from  the  ocean  and  deposited 
the  vapour  aloft  in  clouds,  and  that  later  the  vapour  has 
again  liquefied  and  fallen  upon  the  mountain  tops,  whence 
collecting  together  it  gradually  forms  a  river  which,  on  its 
way  back  to  the  ocean,  will  do  useful  work  in  turning  a 
waterwheel,  etc.  If  we  consider  electricity  as  a  disturb- 
ance of  the  ether  ocean  and  the  dynamo  as  a  pump,  then 
we  have  some  sort  of  analogy,  but  as  was  already  pointed 
out,  it  is  impossible  to  find  any  adequate  analogy  for 
electrical  matters. 

We  agree  to  speak  of  a  current  of  electricity,  not  that 
we  believe  that  there  is  a  flow  in  the  same  sense  as  a 
stream  of  water,  and  while  we  find  it  convenient  to  think 
quite  freely  of  the  carbon  filament  of  a  lamp  as  offering 
so  much  resistance  to  the  current  that  the  carbon  becomes 
heated  and  glows,  we  must  not  imagine  anything  akin  to 
mechanical  friction  and  resistance.  We  must  express  our 
ideas  about  electricity  figuratively,  and  it  is  only  if  we 
forget  that  these  expressions  are  arbitrary  that  any  mis- 
understanding arises.  Indeed,  it  was  only  when  the  early 
theories  were  formed,  no  matter  how  crude  they  may  now 
seem  to  us,  that  advancement  in  matters  electrical  was 
made  possible. 

Electrical  engineers  have  done  much  to  cheapen  the 
cost  of  producing  electric  current  for  lighting  purposes. 
But  within  the  last  few  years  a  great  reduction  in  the 

191 


METALLIC  FILAMENT  LAMPS 

cost  of  electric  light  has  been  accomplished  by  means 
of  glow  lamps  made  upon  a  different  plan.  Instead  of 
employing  a  filament  of  carbon,  very  fine  filaments  of 
rare  metals  have  been  used.  In  one  class  of  lamps, 
of  which  the  osram  is  well  known,  the  metal  is  tungsten. 

The  filaments  of  these  lamps  are  made  of  the  rare 
metals  whose  names  they  bear.  The  metals  are  produced 
from  their  compounds  in  the  form  of  fine  metallic  powder, 
which  is  then  mixed  with  a  suitable  binding  paste,  and 
squirted  through  small  apertures  to  form  the  fine  filaments. 
These  are  placed  in  a  mixture  of  gases,  and  an  electric 
current  is  passed  through  the  filaments,  causing  the  in- 
gredients of  the  binding  material  to  combine  with  the 
gases,  while  the  particles  of  the  rare  metal  become  welded 
together. 

These  metallic  filaments  become  white-hot  very  much 
more  easily  than  the  carbon  filaments.  Some  of  the 
metallic-filament  lamps  now  in  use  take  less  than  one- 
third  of  the  electric  current  required  for  a  carbon-filament 
lamp  of  the  same  candle-power.  This  is  a  great  step  in 
advance,  and  places  electric  light  in  a  very  much  stronger 
position.  If  we  can  continue  making  strides  of  this  kind, 
electric  light  will  soon  have  no  rival. 


192 


CHAPTER  XIX 

ELECTRICITY  FROM  MECHANICAL 
MOTION 

A  powerful  substitute  for  batteries— How  a  dynamo  works— Alter- 
nating currents— An  analogy— Whence  the  magnets  get  their 
current— Advantages  of  alternating  currents. 

SIR    HUMPHRY   DAVY  used  a  battery  of  two 
thousand  cells  to  produce  his  historic  electric  arc, 
and  all  the  early   electric  lamps  were  worked  in 
a  similar  manner  by  batteries.     As  the  upkeep  of  a 
battery  means  the  renewal  of  the  zinc  plates,  etc.,  and 
a  great  deal  of  attention  when  a  large  battery  is  used, 
it  is  quite  clear  that  electric  lighting  would  never  have 
come  into  general  use  unless  some  better  substitute  had 
been  found  to  replace  the   expensive  and  troublesome 
battery. 

The  finding  of  a  suitable  substitute  was  arrived  at  in 
this  way.  Our  great  British  scientist,  the  late  Michael 
Faraday,  found  that  if  a  loop  of  wire  were  moved  up  and 
down  between  the  poles  of  a  magnet  there  was  a  current 
of  electricity  set  up  in  the  wire.  Faraday  pictured  a 
magnetic  field  between  the  poles  of  the  magnet,  and  his 
imagination  filled  this  space  with  "  lines  of  force,"  and  he 
said  it  was  when  the  coil  or  loop  of  wire  passed  through 


SUBSTITUTE   FOR  BATTERIES 

these  imaginary  lines  that  a  current  was  originated.  It 
was  quite  evident  that  it  was  only  as  long  as  he  kept  the 
coil  moving  up  and  down  in  the  magnetic  field  that  the 
current  was  present  in  the  wire. 

The  next  step  was  to  mount  a  coil  of  wire  on  a 
spindle  and  revolve  it  in  the  space  between  the  poles  of  a 
magnet,  and,  as  was  anticipated,  the  effect  was  greatly 
enhanced,  because  the  coil  could  be  made  to  pass  through 
the  imaginary  lines  of  force  much  oftener.  The  little 
magneto  -  electric  machines  sometimes  used  for  medical 
purposes,  but  perhaps  oftener  for  amusement  by  dealing 
out  electric  shocks,  are  simply  arrangements  by  which, 
when  one  turns  a  handle  on  the  outside  of  the  box, 
a  coil  is  made  to  spin  round  in  the  neighbourhood  of  a 
magnet. 

It  then  occurred  to  people  to  make  such  machines  on  a 
very  much  larger  scale,  and  to  use  steam-engines  to  drive 
the  coils  round  at  a  great  speed.  Such  contrivances  were 
called  dynamo-electric  machines,  which  name  we  have 
discarded,  merely  using  the  word  "dynamo'1  (Gr.  dynamis, 
force). 

In  the  small  experimental  machines  at  first  constructed 
ordinary  steel  magnets  were  used,  but  in  order  to  get  a 
stronger  magnetic  field  these  were  soon  replaced  by  electro- 
magnets. A  dynamo  now  consists  of  a  coil  or  coils  of 
wire  mounted  on  a  shaft  or  spindle,  this  part  being  called 
the  armature,  and  driven  round  at  a  high  speed  between 
the  poles  of  an  electro-magnet. 

It  is  all  very  well  to  know  that  there  is  an  electric 
current  set  up  in  the  revolving  coil,  but  how  are  we  to  get 
the  current  away  from  the  continually  moving  coil?  We 


HOW  A  DYNAMO  WORKS 

cannot,  of  course,  have  wires  directly  attached  to  the  coil, 
as  they  would  be  twisted  and  broken  off  as  soon  as  the 
coil  began  to  spin  round.  We  can,  however,  keep  in 
touch  with  the  revolving  coil  by  a  very  simple  arrange- 
ment, as  shown  in  the  diagram  (Fig.  12).  A  single  rect- 


FIG.  12 
PRINCIPLE  OF  A  CONTINUOUS-CURRENT  DYNAMO 

N  and  S  =  North  and  south  poles  of  magnet. 
W  W  =  Rectangular  loop  or  coil  of  wire. 

A  =  Spindle  for  above  to  revolve  upon. 
VV  and  A  together  are  called  the  armature. 

C=Tvvo  bent  metal  contact  pieces  to  which  the  two  ends  of  W 
are  fixed. 

B  B  =  Brushes  which  rub  against  the  revolving  contact  pieces  and 
make  connection  to  the  main  circuit. 

L=A  lamp  in  the  main  circuit. 

angular  loop  of  the  wire  is  here  shown  with  the  two  ends 
attached  to  two  pieces  of  metal,  which  have  been  bent 
round  the  end  of  the  spindle,  but  insulated  from  it  and 
from  each  other;  these  we  will  call  the  contact  pieces. 
Two  flat  pieces  of  metal,  marked  B,  and  called  brushes, 

'9$ 


HOW  A  DYNAMO  WORKS 

although  they  perhaps  look  more  like  combs,  press  against 
the  contact  pieces  on  the  shaft.  On  looking  at  the  dia- 
gram, it  is  now  clear  that  the  current  has  a  path  out  from 
the  loop  by  the  top  brush  through  the  wire  attached, 
which  may  lead  to  a  lamp  and  back  by  the  lower  brush  to 
the  coil,  thus  completing  the  circuit. 

When  the  coil  or  loop  revolves,  the  brushes  will,  of 
course,  keep  in  touch  with  the  coil,  but  they  will  change 
partners  as  regards  contact  pieces  at  each  half-revolution. 
This  changing  of  partners  is  very  convenient,  for  when 
the  coil  in  its  revolutions  enters  the  magnetic  field  in 
front  of  the  north  pole  of  the  magnet,  the  current  flows 
in  one  direction,  while  on  leaving  that  part  of  the  field 
the  current  set  up  is  in  the  opposite  direction,  so  what  we 
really  have  in  the  coil  as  it  spins  round  is  a  current 
pulsating  first  in  one  direction  and  then  in  the  other,  at 
every  half-revolution. 

Again,  looking  at  the  diagram,  it  is  clear  that  if  the 
current  is  passing  out  from  the  loop  or  coil  by  the  top 
contact  piece,  the  brush  touching  it  will  conduct  the 
current  away  to  the  main  circuit,  in  which  are  placed  the 
lamps,  etc.,  while  the  current  returns  by  the  lower  brush. 
Let  us  follow  the  lower  contact  piece  only.  As  it 
leaves  the  lower  brush  the  current  in  the  coil  changes 
in  direction,  so  that  by  the  time  it  reaches  the  top 
brush  the  current,  instead  of  entering  the  coil  by  this 
contact  piece,  is  now  leaving  by  it.  When  the  other 
contact  piece  was  in  the  same  position  it  was  also  the 
exit  for  the  current,  and  so  we  find  that  whichever 
contact  piece  is  uppermost  it  is  the  exit  for  the  cur- 
rent in  the  coil,  and  in  this  way  the  brush  fixed  at  the 

196 


AN  ANALOGY 

top  is  always  leading  out  the  current.  We  therefore 
have  a  current  flowing  in  one  direction  through  the  outer 
circuit. 

If  we  had  two  different  objects,  one  hot  and  the  other 
cold,  and  if  we  imagine  these  two  bodies  changing 
alternately  from  hot  to  cold,  one  always  being  hot  while 
the  other  was  cold,  we  could  place  the  left  hand  on  the 
hot  object  and  the  right  hand  on  the  cold  object,  and 
then  changing  the  position  of  the  hands  just  as  the 
bodies  changed  temperature,  we  could  always  have  the 
left  hand  on  the  object  that  was  hot,  and  the  right  hand 
on  the  cold  object.  If  this  were  possible  in  practice  we 
should  have  a  continuous  flow  of  heat  through  the  body 
from  the  left  hand  to  the  right.  In  similar  fashion  we 
have  a  continuous  flow  of  electricity  from  the  one  brush 
to  the  other,  the  brushes  standing  stationary,  and  the 
changing  contact  pieces  moving  from  one  brush  to  the 
other.  It  is  a  simple  case  of  two  negatives  making 
a  positive. 

Instead  of  consisting  of  flat  pieces  of  metal,  the  brushes 
are  usually  made  of  little  blocks  of  carbon  carried  in 
a  suitable  holder,  and  these  give  a  splendid  rubbing 
contact  with  the  armature's  contact  pieces.  Instead  of 
there  being  only  two  contact  pieces,  as  in  the  diagram, 
a  large  armature  is  built  up  of  a  number  of  separate 
coils,  each  coil  having  two  contact  pieces,  arranged  so 
that  the  brushes  simultaneously  touch  the  two  ends  of 
one  coil,  then  the  two  ends  of  the  coil  following  it,  and 
so  on.  Instead  of  having  only  one  electro-magnet  sur- 
rounding the  revolving  coil,  it  is  now  common  to  have 
several  magnets  arranged  to  act  together,  so  that  the 

197 


HOW  A   DYNAMO  WORKS 

coil  passes  the  poles  of  each  magnet  in  rotation,  but 
the  general  principle  is  represented  in  the  simple  diagram 
(Fig.  12). 

Remembering  that  in  the  revolving  coil  there  is  really 
a  quickly  pulsating  current,  first  in  one  direction  and  then 
in  the  other,  let  us  try  and  get  at  this  current  directly 
without  converting  it  to  a  continuous  current.  If  we 
take  away  the  two  contact  pieces,  shown  in  the  diagram, 
and  place  two  complete  rings  alongside  of  each  other  on 
the  shaft,  insulating  them  from  each  other  and  from  the 
shaft,  we  may  now  fasten  one  end  of  the  coil  to  each  of 
these  ring  contact  pieces.  If  we  then  place  the  top  brush 
in  contact  with  one  ring  and  the  lower  brush  against  the 
other  ring,  it  is  clear  that  each  brush  will  always  remain 
in  contact  with  its  own  ring,  and  there  will  be  no  inter- 
changing of  partners,  as  was  the  case  with  the  first 
arrangement.  Consequently  there  will  be  no  reversal  of 
the  current  coming  from  the  coil,  so  we  shall  have  a 
pulsating  current  in  the  outer  mains  just  as  we  have 
in  the  revolving  coil  itself.  Such  a  pulsating  current, 
first  in  one  direction  and  then  in  the  other,  is  called  an 
alternate  or  alternating  current,  and  a  dynamo  arranged 
with  these  complete  rings  is  called  an  alternator  or  an 
alternating  dynamo.  The  arrangement  of  contact  pieces 
and  brushes  on  a  continuous-current  dynamo  is  termed 
the  commutator,  as  it  commutes  or  changes  the  current. 
For  diagram  of  alternator  see  page  202. 

Before  leaving  these  dynamos  to  see  what  we  can  do 
with  them,  there  is  an  interesting  point  to  note.  Where 
is  the  large  electro-magnet  to  get  electricity  from  to 
produce  its  magnetism  ?  We  simply  steal  some  of  the 

198 


WHENCE  MAGNET  GETS  CURRENT 

current  that  the  dynamo  is  generating  and  pass  it  round 
the  magnet.  That  is  all  very  well  when  we  once  have 
the  currents  coming  from  the  dynamo,  but  how  are  we 
to  get  it  started  ?  When  a  dynamo  has  once  been  used 
the  iron  of  the  magnet  always  retains  a  trace  of  magnet- 
ism, sufficient  to  set  up  a  very  weak  field.  When  the 
coil  revolves  very  rapidly  in  this  a  correspondingly  weak 
current  is  produced,  which  goes  to  augment  the  magnet 
and  so  on  till  very  quickly  the  dynamo  is  in  full 
working  order.  When  a  dynamo  is  constructed  there 
is  usually  sufficient  magnetism  in  the  iron  iteelf  to  set 
up  a  weak  field  at  the  very  outset,  but  if  not  it  could 
easily  be  momentarily  coupled  to  the  electric  supply 
mains. 

It  is  very  convenient  to  be  able  to  feed  the  magnet 
with  the  current  which  it  is  itself  producing,  but  we  can 
only  do  this  with  a  continuous -current  dynamo.  The 
current  going  round  the  magnet  must  be  all  in  one  direc- 
tion, and  so  where  the  electricity  is  being  led  away  from 
the  dynamo  as  an  alternating  current  it  will  not  do  to 
pass  this  round  the  magnet.  To  work  an  alternating 
dynamo  we  therefore  require  to  have  a  separate  exciter, 
which  consists  of  a  small  continuous-current  dynamo,  or, 
if  there  be  a  number  of  alternating  dynamos  working  in 
one  station,  it  is  more  convenient  to  run  one  continuous 
dynamo  to  feed  all  the  magnets. 

It  might  seem  very  inconvenient  to  have  a  pulsating 
current  continually  changing  its  direction  in  the  circuit, 
but  while  at  first  this  class  of  dynamo  was  left  severely 
alone  it  has  of  recent  years  come  well  to  the  front. 
Before  considering  the  advantages  which  have  brought 

199 


ALTERNATING  CURRENTS 

this  dynamo  into  a  prominent  position  to-day,  let  us  see 
what  takes  place  in  a  circuit  in  which  an  alternating 
current  is  at  work. 

If  a  small  glow-lamp  be  put  in  the  circuit  leading  from 
an  alternating  dynamo,  arranged  as  just  described,  and 
if  the  alternations  of  the  current  be  slow,  there  will,  of 
course,  be  a  great  unsteadiness  in  the  light,  as  the  current 
will  practically  cease  at  the  moment  of  change  from  one 
direction  to  the  other.  If,  however,  the  armature  coil 
is  driven  round  at  a  very  high  speed,  the  current  may  be 
made  to  change  its  direction  as  often  as  fifty  times  in  one 
second.  With  such  rapid  alternations  the  light  will  be 
perfectly  steady  as  far  as  we  are  able  to  detect  it  with 
our  eyes,  for  at  each  fiftieth  part  of  a  second  we  have 
a  light  thrown  upon  the  retinas  of  our  eyes,  and  as  the 
image  of  a  bright  light  will  not  fade  away  for  about  one- 
tenth  of  a  second  each  of  the  fifty  pulsations  in  the  lamp 
will  overlap  its  predecessor,  and  we  may  imagine  our  eyes 
receiving,  as  it  were,  a  perfectly  continuous  cinematograph 
impression  of  a  quickly  pulsating  light. 

Even  at  this  speed  of  fifty  alternations  in  one  second, 
there  is  bound  to  be  a  sudden  rise  and  fall  in  the  current 
at  each  pulsation,  although  not  visible  to  the  eye.  For 
some  purposes  even  this  would  be  detrimental,  but  this 
further  difficulty  is  overcome  by  winding  two  separate 
coils  on  the  one  armature  and  arranging  them  so  that 
when  the  current  is  at  its  turning  point  in  the  one  coil 
it  will  be  at  its  maximum  in  the  second  coil,  or  better 
still,  if  three  separate  coils  and  pairs  of  brushes  be  used 
the  defect  can  be  further  reduced. 

We  can  imagine  an  alternating  current  as  a  wave 

200 


ALTERNATING   CURRENTS 

swinging  to  and  fro,  and  this  we  call  its  phase,  so  that 
when  two  coils  are  used  and  there  is,  as  it  were,  two  separate 
waves  overlapping  each  other,  this  is  called  a  two-phase 
current,  or  we  may  speak  of  a  machine  with  three  coils 
as  a  three-phase  alternating  dynamo. 

When  describing  the  principle  of  the  arc-lamp,  it  was 
noted  that  particles  of  carbon  broke  away  from  the  point 
of  the  carbon  pencil  at  which  the  current  enters  the  arc, 
and  it  is  therefore  obvious  that  this  carbon  will  waste 
away  very  much  quicker  than  its  neighbour,  in  point  of 
fact,  about  twice  as  quickly.  If  we  now  use  an  alternating 
current,  the  current  will  be  first  entering  at  one  pencil 
and  then  at  the  other,  so  that  both  will  waste  away 
equally,  which  is  a  considerable  advantage  in  favour  of 
an  alternating  dynamo  as  far  as  arc-lighting  is  concerned. 

Another  advantage,  which  has  been  recognised  in  these 
alternators,  is  that  we  can  conveniently  obtain  a  much 
higher  voltage  or  pressure,  which  makes  the  distribution 
of  current  over  a  long  distance  much  easier,  and  the 
alternating  current  is  very  simply  changed  from  a  high 
voltage  to  a  lower  one,  or  vice  versa. 

Of  course  the  alternating  current  is  of  no  use  for 
some  purposes,  as,  for  instance,  electro-plating,  in  which 
process  a  steady  current  is  required  to  carry  the  metal 
over  from  the  plating  material  to  the  article  being 
plated.  However,  an  alternating  current  may  be  made 
to  drive  a  motor,  which  in  turn  drives  a  continuous- 
current  dynamo,  and  in  this  way  a  current  of  the  one 
class  may  be  altered  to  a  current  of  the  other  class  at 
very  little  loss. 

In  speaking  of  these  dynamos,  I  have  only  mentioned 

201 


ALTERNATING   CURRENTS 

a  fixed  magnetic  field  and  a  rotating  armature  in  which 
the  current  is  induced,  but  it  is,  of  course,  as  easy  to  have 
these  two  reversed,  and  so  we  have  some  dynamos  in 
which  the  electro-magnets  form  the  moving  part,  the 
coils  in  which  the  current  is  induced  being  stationary. 


FIG.  13 
PRINCIPLE  Or  A  DYNAMO  SUlTLVING  ALTERNATING  CURRENT 

N  and  S  =  North  and  south  poles  of  magnet. 
WW  =  Rectangular  loop  or  coil  of  wire. 

A  =  Spindle  for  above  to  revolve  upon. 
W  and  A  together  are  called  the  armature. 

(When  revolved  in  the  magnetic  field  an  electric  current  is  produced  in 
the  coil  WW,  the  current  changing  its  direction  at  each  half  revolution.) 
RR  =  Two  metal  rings ;  one  fixed  to  each  end  of  coil  WW. 
BB  =  Brushes  which  press  against  the  revolving  rings  and  thus 
make  connection  between  the  revolving  coil  and  the  outer 
or  main  circuit. 

L  =  A  lamp  in  the  main  circuit. 

(The  current  in  the  main  circuit  will,  of  course,  alternate  in  direction 
just  as  in  the  revolving  coil.) 


202 


CHAPTER  XX 

MECHANICAL  MOTION  FROM 
ELECTRICITY 

A  mysterious  machine— How  electricity  makes  the  motor  go-— An 
explanatory  experiment— A  dynamo  may  be  a  motor — The  source 
of  the  motion — A  lecturer's  amusing  experience — An  early  idea — 
A  motor  requires  a  dynamo — A  great  advantage — Gigantic  power 
carried  by  a  dormant  wire — Present  clumsy  methods— A  coming 
revolution. 

WHEN  one  goes  into  an  engine-room  and  looks 
at  an   engine  at  work   there  is — to   many — a 
peculiar  fascination  about  the  machine,  though 
not  because  of  any  mystery,  for  we  are  all  familiar  with 
the  expansive  power  of  steam  which  gives  the  impelling 
force  to  the  piston ;  but  when  one  watches  the  armature 
of  an  electric  motor  spinning  quietly  round  at  a  high 
speed,  one  does  feel  a  sense  of  mystery,  and  it  is  not  sur- 
prising to  find  that  the  electric   motor  is  a  source  of 
wonderment  to  the  majority  of  people. 

Of  all  the  subjects  connected  with  electricity,  I  have 
found  that  the  outsider  seems  particularly  interested  to 
learn  how  electricity  can  drive  machinery,  and  make  a 
train  or  car  to  go.  Whether  it  has  been  a  deputation  of 
artisans  from  the  city  with  a  request  for  a  lecture,  or  a 
conversation  with  an  intelligent  farmer  in  a  country 

203 


A  MYSTERIOUS   MACHINE 

district,  the  one  question  which  seems  to  be  uppermost  is 
just,  "  How  does  electricity  make  the  motor  go  ?"  If  we 
are  content  to  know  how  it  is  done,  to  the  same  extent  as 
most  people  understand  how  a  steam-engine  works,  then 
there  is  no  difficulty. 

In  explaining  the  principle  of  the  steam-engine  one 
might  point  to  a  kettle  of  boiling  water  on  the  fire,  the 
lid  of  which  was  being  repeatedly  lifted  by  the  expanding 
steam.  To  explain  the  electric  motor  I  would  point  to  a 
little  magnetic  needle  being  attracted  by  a  magnet  brought 
near  to  it,  and  say  that  that  is  the  way  electricity  makes 
the  motor  go.  It  is  simply  a  case  of  magnetic  attractions 
and  repulsions.  I  take  the  little  magnetic  needle  pivoted 
on  its  stand,  and  having  painted  the  north  pole  red  so 
that  it  may  be  easily  distinguished,  I  bring  a  steel  bar- 
magnet  near  to  it.  I  first  of  all  hold  the  south  pole  of 
the  bar-magnet  towards  the  north  pole  of  the  needle,  and 
the  needle  at  once  swings  round  towards  it,  but  when  it 
comes  round  to  the  bar-magnet  I  quickly  turn  the  latter 
round  in  my  hand,  thus  pointing  its  north  pole  towards 
the  needle.  This  pole  now  repels  the  north  pole  of  the 
needle,  causing  it  to  continue  on  its  circular  path,  and 
with  a  little  practice  I  soon  find  I  can  set  the  little 
magnetic  needle  spinning  round  on  its  centre.  This  is 
just  the  principle  of  what  happens  in  a  motor.  Instead 
of  a  little  magnet  balanced  on  a  pivot,  there  is  a  coil  of 
wire  mounted  on  a  spindle,  and  in  an  early  chapter  we 
saw  that  a  coil  of  wire,  having  a  current  of  electricity 
flowing  in  it,  was  in  every  respect  a  magnet.  In  place  of 
the  bar-magnet  which  I  held  in  my  hand,  there  is  a  large 

204 


1  1 

OD  ~ 

i  3 

1  2 


ELECTRICITY  MAKES   MOTOR  GO 

electro-magnet,  the  poles  of  which  surround  the  coil- 
magnet  mounted  on  its  spindle.  It  will  not  be  convenient 
to  keep  changing  the  poles  of  this  huge  magnet  as  I  did 
with  the  bar-magnet,  but  if  we  let  this  magnet  remain 
constant,  and  we  change  the  direction  of  the  current  in 
the  coil-magnet  at  each  half-revolution  instead,  the  result 
will  be  the  same.  It  will  be  remembered  that  when  we 
pass  a  current  of  electricity  through  a  coil  in  one  direc- 
tion, the  one  face  of  coil  becomes  a  north  pole  and  the 
other  a  south  polej  but  when  we  reverse  the  current,  send- 
ing it  through  the  coil  in  the  opposite  direction,  then  the 
north  and  south  poles  change  places. 

It  is  apparent  that  this  motor,  which  we  have  now  built 
up  in  our  imaginations,  is  simply  a  dynamo :  a  large 
electro-magnet  with  an  armature  or  coil  between  its 
poles.  But  we  are  going  to  do  just  the  reverse  of  what 
we  did  with  the  dynamo.  We  caused  the  armature  of 
the  dynamo  to  be  driven  round  at  a  great  speed,  and  we 
led  away  a  current  of  electricity  from  the  revolving  coil. 
We  had  a  rapidly  changing  or  alternating  current  in  the 
coil,  but  by  means  of  the  commutator  and  brushes  we  led 
the  current  out  in  one  direction  into  the  mains.  In  the 
case  of  the  motor,  we  are  now  going  to  lead  the  same 
kind  of  current  back  to  the  brushes,  taking  the  current 
from  another  dynamo,  and  as  soon  as  the  current  enters 
the  armature-coil  its  poles  will  be  attracted  by  the  poles 
of  the  large  electro -magnet  surrounding  it,  and  it  has 
been  so  placed  that  this  attractive  pull  will  cause  it  to 
turn  round  on  its  spindle  half  a  revolution.  At  this 
point  the  armature  coil  will  have  its  ends  in  touch  with 

205 


AN  EXPLANATORY  EXPERIMENT 

the  opposite  brushes  from  which  it  started,  and  so  the 
current  is  reversed  in  the  armature,  causing  it  again  to 
turn  a  half-revolution.  It  is  now  back  to  the  position 
it  started  from,  and  so  sets  off  once  more,  the  current 
reversing  at  every  half-revolution.  In  this  way  it  soon 
gathers  speed;  the  quicker  it  goes,  the  oftener  will  it 
reverse  its  points  of  contact  with  the  brushes,  so  the 
revolving  coil  really  becomes  a  magnet,  changing  its 
poles  at  an  almost  incredible  speed.  Referring  again  to 
the  simple  explanatory  experiment  from  which  we  set  out, 
it  is  just  as  though  I  held  the  bar- magnet  steady,  having 
a  separate  bar-magnet  stationed  with  its  opposite  pole  at 
the  other  side  of  the  magnetic  needle,  or  it  might  be 
simpler  to  think  of  a  large  horseshoe  magnet  with  its 
legs  spread  out  to  allow  the  magnetic  needle  to  spin 
round  on  its  centre  between  the  poles.  Thus  having  a 
steady  magnetic  field  or  influence,  it  is  necessary  that 
the  magnetic  needle,  when  turning  into  the  position  to 
which  it  is  attracted  by  the  magnet,  should  then  re- 
verse its  poles  and  receive  a  further  attraction  to  make 
it  continue  on  its  journey.  Of  course  it  is  impossible 
to  have  a  permanent  magnetic  needle  changing  its  poles 
continually  to  suit  our  convenience,  but  the  magnet 
formed  by  a  simple  coil  of  wire,  carrying  a  current, 
will  behave  in  this  manner,  and  so  electric-motors  are 
not  only  possible,  but  thoroughly  efficient  and  powerful 
engines. 

A  boy  holding  a  magnet  near  to  the  magnetic  needle 
of  a  small  pocket  or  pendant  compass  can  make  the 
needle  move  round,  by  carefully  reversing  the  position  of 

206 


AN  EARLY  IDEA 

the  poles  of  his  magnet  he  may  make  the  magnetic  needle 
spin  round;  it  is  the  same  power  which  makes  the 
motor  go. 

By  applying  mechanical  motion  to  a  dynamo,  in  revolv- 
ing its  armature,  we  get  electricity,  and  by  giving  the 
same  machine  electricity,  its  armature  revolves  and  we 
get  mechanical  motion.  In  the  latter  case  we  call  the 
dynamo  a  motor.  Of  course,  in  actual  practice  there 
are  differences  of  detail  in  construction  depending  upon 
whether  the  machine  is  to  be  used  as  a  dynamo  or  as  a 
motor. 

When  one  becomes  accustomed  to  the  idea  that  a  coil 
of  wire  carrying  an  electric  current  is  a  real  magnet, 
then  there  is  no  difficulty  in  understanding  the  principle 
of  electric  motors,  but  I  trust  that  the  foregoing  ex- 
planation will  not  meet  with  the  same  fate  as  did  one 
explanation  of  this  matter  given  in  a  lecture  I  heard 
recently.  The  lecturer  had  been  requested  by  the  chair- 
man, a  bailie  in  the  town  in  which  the  lecture  was  being 
delivered,  to  explain  how  electricity  made  the  cars  go. 
The  lecturer  explained  the  matter  in  his  own  way,  and 
he  no  doubt  was  somewhat  surprised  and  amused  when 
the  worthy  bailie,  in  proposing  a  vote  of  thanks,  said 
that  the  lecture  had  been  most  interesting,  but  for  the 
life  of  him  he  could  not  see  yet  what  it  was  that  made 
the  cars  go. 

When  speaking  of  a  dynamo  and  a  motor  being  exactly 
the  converse  of  each  other  in  action,  it  is  interesting  to 
note  that  if  two  electro-static  machines,  such  as  those 
described  in  an  early  chapter,  be  connected  together  by 

307 


MOTOR  REQUIRES  A  DYNAMO 

wires,  so  that  the  high-tension  charge,  generated  by  the 
one  machine  when  rotated,  is  led  to  the  collectors  of  the 
second  glass  or  vulcanite  plate  machine,  the  latter  will 
begin  to  rotate  also,  its  plates  being  attracted  round  by 
the  charge  on  its  collectors.  The  reversibility  of  the 
dynamo  and  motor  should  not  really  appeal  to  us  as  any- 
thing strange,  for  we  have  the  same  converse  actions  in 
everyday  life,  as,  for  instance,  when  a  windmill  is  driven  by 
the  wind,  thereby  producing  mechanical  motion,  while  on 
the  other  hand  we  may  apply  mechanical  motion  to  a 
windmill  or  fan,  driving  it  round  and  producing  a  wind, 
as  is  demonstrated  by  a  ventilating  fan. 

In  the  early  days  of  electricity  the  distinguished 
American  professor,  Joseph  Henry,  constructed  an  electric 
motor  on  quite  a  different  principle  from  that  which  we 
have  been  considering.  Imagine  a  pair  of  beam  scales 
with  two  iron  pans,  and  at  a  little  distance  underneath  each 
an  electro-magnet.  If  an  electric  current  be  sent  first  to 
one  magnet  and  then  to  the  other,  and  so  on  alternately, 
the  beam  of  the  scales  will  be  made  to  rock  or  see-saw, 
just  as  one  sees  in  an  old  beam  engine.  The  up-and-down 
motion  of  the  beam  turns  a  crank  which  drives  the  fly- 
wheel round.  This  early  electro-motor  was  arranged 
to  automatically  switch  the  current  from  one  magnet  to 
the  other  at  each  stroke,  but  the  principle  of  the  machine 
entailed  a  very  great  waste  of  power.  Of  course,  the 
machine  was  not  made  in  the  form  of  a  pair  of  scales,  but 
the  principle  was  just  as  described. 

Whenever  we  see  an  electric  motor  at  work,  whether  in 
a  workshop  or  factory  driving  machinery,  or  on  a  tram- 


POWER  BY  DORMANT  WIRE 

way  car  propelling  it  along,  we  may  be  quite  sure  that 
there  is,  possibly  at  some  considerable  distance,  a  dynamo 
being  driven  round  by  an  engine,  and  also  that  there 
must  be  a  wire  or  cable  carrying  the  electric  current  from 
the  dynamo  to  the  motor.  Of  course,  it  is  possible  to 
drive  a  motor  by  means  of  a  powerful  storage  battery,  as 
is  often  done,  but  not  economically. 

One  might  ask  what  is  the  use  of  first  driving  a 
dynamo  by  an  engine  and  then  making  the  dynamo  drive 
a  motor.  It  is  clear  that  we  cannot  get  as  much  power 
from  the  motor  as  we  get  from  the  engine  itself,  for  there 
must  be  some  waste  of  power  in  friction,  etc.,  both  in 
the  dynamo  and  the  motor.  There  is  certainly  nothing 
to  be  gained  in  this  direction,  but  the  actual  loss  in 
power  is  surprisingly  small,  the  motor  giving  about 
ninety  horse-power  for  every  hundred  horse-power  of  the 
engine. 

The  dynamo  and  motor  are,  however,  of  very  great 
advantage,  because  they  give  us  a  most  convenient  means 
of  conveying  power  to  a  distance.  We  can  have  a  power- 
ful engine  with  a  dynamo  fixed  at  some  convenient  place, 
and  from  this  station  we  can  distribute  power  to  anyone 
requiring  it.  We  can  convey  the  current  to  a  wire 
stretched  along  a  roadway  or  public  street,  and  thus 
allow  the  motor  underneath  a  moving  tramway  car  to 
keep  in  touch  with  the  distant  dynamo. 

Before  the  days  of  electrical  transmission  of  power  it 

was  often  very  difficult  to  drive  machinery  in  different 

parts  of  a  works  without  fitting  up  various  engines  in 

different  places.     It  is  interesting  to  note  in  some  of  the 

o  209 


POWER  BY  DORMANT  WIRE 

older  factories  how  our  grandfathers  had  to  arrange  long 
belt  drives  or  long  connecting  shafts  from  one  building 
to  another  to  convey  power.  If  some  engineer,  a  genera- 
tion ahead  of  his  time,  had  come  along  and  said  that  he 
could  save  them  all  this  trouble,  for  a  fixed  and  station- 
ary wire  could  carry  the  necessary  power  to  any  desired 
distance,  I  have  no  doubt  our  grandfathers  would  have 
counted  him  a  knave,  or  would  possibly  have  advised  his 
friends  to  take  better  care  of  him.  To-day  there  seems 
little  to  marvel  at  in  this  possibility  of  carrying  power 
along  a  simple  wire,  for  we  have  become  quite  familiar 
with  such  facts  in  everyday  life.  How  convenient  to  be 
able  to  carry  power  by  fixed  wires  to  a  ventilating  fan  on 
the  wall  or  roof  of  a  building,  far  away  from  any  source 
of  power.  What  a  saving  is  made  in  being  able  to  take 
a  drill  or  other  tool  to  any  part  of  a  ship's  hull,  or  to 
some  out-of-the-way  portion  of  a  bridge  under  con- 
struction, using  wires  to  carry  the  power  from  the  distant 
generator  to  the  tool. 

At  present  we  convey  great  train-loads  of  coal  from 
our  coalfields  across  the  country  to  our  manufacturing 
centres.  One  sometimes  sees  heavy  train-loads  of  coal 
passing  each  other  in  opposite  directions,  one  lot  leaving 
a  town  and  another  lot  entering  it.  Then  we  have  to 
cart  the  coal  about  from  one  place  to  another,  and  all 
this  carrying  means  a  great  expenditure  of  energy.  I 
think  one  might  safely  prophesy  that  some  future 
generation  will  marvel  that  we  were  content  with  such 
clumsy  methods.  It  would  be  possible  to  convert  all  the 
coal  into  electrical  power  at  the  pit-head,  and  from  there 

2IO 


By  permission  o/  the  U.S.  Metallic  Packing  Co.,  Ltd. 

A    PORTABLE    ELECTRIC   DRILL 

If  a  piece  of  work  cannot  be  taken  into  the  engineering  shop,  the  shop 
can  practically  be  taken  to  the  work.  What  a  contrast  between  the 
smart  work  of  an  electric  drill,  as  shown  above  at  work  on  the  stern 
of  a  steamer,  and  the  many  weary  hours  of  hand  labour  at  one  time 
necessary ! 


A  COMING  REVOLUTION 

distribute  it  for  motive,  lighting,  or  heating  purposes  to 
all  the  surrounding  towns. 

Where  no  coalfields  exist  within  a  hundred-mile  radius, 
the  coal  could  be  carried  to  immense  generating  stations, 
supplying  a  great  many  towns  covering  a  large  area. 
Already  there  are  indications  of  things  moving  in  this 
direction. 

Sir  J.  J.  Thomson  has  taken  a  much  longer  look 
ahead  in  his  address  to  the  British  Association  at  Win- 
nipeg in  1909.  Referring  to  the  enormous  quantity  of 
energy  lavished  upon  this  planet  by  the  sun,  he  pointed 
out  that,  according  to  the  measurements  of  Langley,  when 
the  sun  was  high  and  the  sky  clear  the  heat  energy 
received  was  equivalent  to  seven  thousand  horse-power 
per  acre.  Following  this  up,  Sir  J.  J.  Thomson  said : 
"Though  our  engineers  have  not  yet  discovered  how 
to  utilise  this  enormous  supply  of  power,  they  will,  I  have 
not  the  slightest  doubt,  ultimately  succeed  in  doing  so ; 
and  when  coal  is  exhausted  and  our  water  power  in- 
adequate, it  may  be  that  this  is  the  source  from  which  we 
shall  derive  the  energy  necessary  for  the  world's  work. 
When  that  comes  about,  our  centres  of  industrial  activity 
may  perhaps  be  transferred  to  the  burning  deserts  of  the 
Sahara,  and  the  value  of  land  determined  by  its  suit- 
ability for  the  reception  of  traps  to  catch  sunbeams." 


211 


CHAPTER  XXI 
ELECTRIC  RAILWAYS,  NIAGARA,  ETC. 

The  astonished  Chinaman — The  distant  source  of  energy— Power 
stations— How  the  power  reaches  the  car — Where  the  danger  lies 
— Electric  railways— The  "live  rail"— Higher  speeds  will  be 
demanded — Mono-rail  system — Electric  motor-cars — Canal  haulage 
— Electric  launches— Niagara  Falls— How  the  power  is  distributed 
— Latest  developments  at  Niagara. 

WHEN  the  man  in  the  street  sees  an  electric 
tramway  car  for  the  first  time  he  thinks  it 
peculiarly  mysterious,  even  although  he  may 
be  aware  that  there  is  an  electric  motor  fixed  below  the 
car  driving  its  wheels  round.  He  does  not  have  the  same 
feeling  about  a  horse-drawn  car  or  a  puffing  engine,  for 
the  source  of  energy  in  these  cases  is  very  apparent.  A 
cable  haulage  car  does  not  even  call  forth  surprise,  as  he 
knows  of  the  endless  rope,  continually  travelling  along  in 
an  underground  channel,  to  which  the  driver  may  attach 
his  car  and  let  go  at  will.  The  man  in  the  street  is  more 
learned  than  the  Chinaman  of  whom  Sir  Oliver  Lodge 
tells  the  story,  that  when  he  first  saw  a  cable-car  in  the 
streets  of  Chicago  he  regarded  it  for  some  time  with 
open-mouthed  astonishment,  and  then  exclaimed,  "No 
pushee — no  pullee — go  like  mad!"  That  the  ordinary 
man,  however,  does  puzzle  over  the  electric  car  is  demon- 
strated by  a  conversation  reported  to  have  been  overheard 

212 


DISTANT  SOURCE   OF  ENERGY 

in  London  between  two  Irish  labourers.  In  discussing 
the  principle  of  electric  tramways,  one  of  the  men  ex- 
plained that  it  was  "  that  sort  of  fishing-rod  on  the  top 
that  makes  the  business  go."  He  evidently  supposed  that 
the  trolley  pole  was  pushing  the  car  along  in  some 
mysterious  way.  It  is  really  because  the  source  of  energy 
is  not  apparent  that  an  electric  car  has  a  mysterious 
appearance.  The  motor-man  merely  turns  a  switch  and, 
no  matter  how  heavily  the  tram  is  laden,  off'  it  goes. 

Whenever  we  see  anything  in  motion  we  know  there 
must  be  an  expenditure  of  energy  going  on.  The  car  is 
expending  a  great  deal  of  energy,  and  we  know  there 
must  be  a  corresponding  amount  of  energy  being  gener- 
ated behind  the  scenes.  The  car  may  be  miles  from  the 
source,  but  at  the  distant  generating  station  there  is 
much  activity.  The  stokers  are  at  work  looking  after  the 
boilers,  although  their  work  is  greatly  lightened  by  the 
modern  mechanical  appliances,  which  feed  forward  the 
coal,  weigh  it,  and  then  shoot  it  into  the  furnace.  When 
we  stand  and  look  along  a  great  row  of  furnaces  and 
boilers  at  a  generating  station,  and  when  we  think  of  the 
tremendous  expansive  power  of  steam,  we  understand  the 
source  of  energy  for  the  cars.  Close  to  the  boiler-house 
we  find  the  engine-room,  where  we  see  several  huge 
engines  at  work,  each  engine  being  equivalent  to  four 
or  five  thousand  horse-power.  Here  we  see  enough 
mechanical  motion  to  drive  all  the  cars  in  the  town.  But 
how  is  this  power  to  be  conveyed  to  the  cars?  Each 
engine  is  directly  coupled  to  a  large  dynamo,  and  from 
these  dynamos  wires  or  cables  conduct  the  electricity 
along  the  car  routes.  If  the  town  be  a  large  one  it  is 

213 


POWER  STATIONS 

general  to  have  one  central  station,  where  all  the  boilers 
and  engines  are  placed,  and  where  all  the  necessary  current 
is  generated.  To  transmit  this  power  economically  to  a 
distance  it  is  necessary  to  have  the  current  at  a  very  high 
pressure.  From  this  station  the  high  voltage  current  is 
led  away  to  a  number  of  different  sub-stations  placed  at 
convenient  points  on  the  various  car  routes.  The  large 
cables  carrying  this  highly  dangerous  current,  which  is 
probably  about  6,500  volts,  are  well  buried  under  the 
ground. 

In  these  sub-stations  this  high-pressure,  alternating 
current,  received  from  the  generating  station,  is  first  of  all 
transformed  or  "  stepped  down  "  to  the  low  pressure  of  a 
few  hundred  volts.  To  accomplish  this  transformation 
there  is  no  moving  machinery.  The  current  merely  passes 
through  a  stationary  coil  of  wire  and  induces  another 
current  in  a  neighbouring  coil,  the  change  of  voltage  or 
pressure  being  obtained  by  there  being  a  different  num- 
ber of  turns  of  wire  in  the  two  coils.  These  coils  are 
called  static-transformers,  and  their  principle  is  the  same 
as  that  of  the  induction  coils  explained  in  a  former  chap- 
ter. There  is  no  need  of  a  making  and  breaking  of  con- 
tact, as  the  current  itself,  being  an  alternating  one,  is 
starting  in  one  direction  and  then  in  the  other  alternately, 
producing  the  constantly  changing  field  of  influence  re- 
quired to  set  up  a  current  in  the  neighbouring  coil. 

The  very  high  pressure  current,  reaching  the  sub- 
station by  these  underground  cables,  has  now  been  trans- 
formed to  a  low  pressure,  but  it  is  still  an  alternating  or 
to-and-fro  current,  whereas  it  is  usually  preferred  to  send 
a  continuous  or  uni-directional  current  for  driving  the 

214 


HOW  POWER  REACHES  THE  CAR 

motors  on  the  cars.  This  further  transformation  is  easily 
effected,  for  we  have  only  to  use  this  current  to  drive  an 
alternating  motor,  to  which  we  couple  a  continuous- 
current  dynamo,  from  the  brushes  of  which  we  may  now 
lead  away  a  convenient  current  for  the  tramway  motors. 
This  sub-station  has  not  generated  any  of  the  power,  it 
has  merely  altered  the  condition  of  the  current  to  suit 
requirements,  and  the  loss  of  power  in  doing  so  is  sur- 
prisingly small.  This  final  current  is  then  led  out  by 
underground  cables,  from  these  dynamos,  along  the  car 
routes.  At  intervals  along  the  route>  where  one  sees  a 
large  metal  box  at  the  side  of  the  road,  the  current  is  fed 
on  to  the  overhead  trolley  wire.  The  trolley  pole,  which  is 
attached  to  the  roof  of  the  car,  keeps  in  touch  with  this 
bare  trolley  wire,  and  the  current  passes  down  a  wire 
from  this  pole  to  the  switch-box  beside  the  motor-man. 
He  may  pass  the  current  direct  to  the  motor  under  his 
car,  in  which  case  it  goes  off  at  full  speed,  or  he  may  pass 
the  current  through  a  number  of  different  resistances, 
only  allowing  a  certain  amount  of  current  to  get  to  the 
motor.  By  moving  his  controlling  switch  he  thus  throws 
more  or  less  of  these  resistances,  or  coils  of  wire,  into 
the  circuit,  and  he  is  thereby  able  to  regulate  the  speed 
of  his  motor.  After  passing  through  the  motor  the 
current  is  led  by  way  of  the  axles  and  wheels  of  the  car 
to  the  rails.  It  is  then  led  off  by  cables  at  short  intervals 
and  thus  conducted  back  to  the  power-house. 

Instead  of  carrying  the  trolley  wire  overhead,  it  may  be 
placed  in  a  channel  under  the  track,  with  an  open  slot 
through  which  a  connecting  rod  may  pass,  the  appearance 
of  the  track  being  the  same  as  for  cable  haulage,  but  this 

215 


WHERE  THE  DANGER  LIES 

underground  trolley  wire  is  naturally  a  much  more  expen- 
sive system  to  install.  There  is  really  very  little  danger 
from  the  overhead  wires,  as  they  are  well  looked  after,  being 
constantly  examined  and  kept  in  good  repair.  The  chief 
source  of  danger  is  in  telephone  wires  falling,  but  guard 
wires  are  put  up  right  along  the  track,  immediately  over 
the  trolley  wire,  to  prevent  the  telephone  wires  getting  in 
contact  with  the  "  live  "  wire.  No  doubt  when  the  Govern- 
ment take  over  the  telephones  in  this  country  the  over- 
head network  of  telephone  wires,  existing  in  some  large 
cities,  will  entirely  disappear,  being  placed  underground, 
so  that  this  source  of  danger  may  be  removed  very  soon. 
Already  horse-drawn  tramway  cars  seem  quite  out  of 
date,  although  London  has  not  yet  dispensed  with  all 
these  "  antiquated  "  vehicles.  These  are,  however,  fast 
disappearing,  and  even  in  quite  small  towns  one  finds  a 
modern  system  of  electric  cars.  It  is  almost  as  certain 
that  the  steam  locomotive  will  be  banished  from  the  rail- 
way tracks.  How  convenient  for  a  railway  locomotive  to 
receive  its  energy  "ready  made,"  by  simply  keeping  in 
touch  with  a  stationary  wire  or  rail.  If  desired  there 
need  not  be  any  separate  locomotive,  for  the  passenger 
car  may  carry  the  electric  motor  itself,  just  as  the  tram- 
way car  does.  Electric  railways  have  been  built  on  the 
Continent  with  overhead  trolley  wires,  but  engineers  in 
this  country  have  preferred  a  third  rail,  placed  near  the 
ground,  to  act  as  the  conductor  of  the  current.  It  is  this 
rail  which  is  called  the  "  live  rail,"  and  which  at  the  first 
caused  considerable  alarm.  As  electric  traction  becomes 
more  common,  people  will  learn  to  keep  clear  of  live  rails, 
just  as  one  would  avoid  a  red-hot  poker.  If  this  "  live 

216 


ELECTRIC  RAILWAYS 

rail "  danger  will  only  scare  trespassers  off  the  railway 
tracks  altogether  it  may  be  the  means  of  preventing  much 
loss  of  life  annually. 

It  is  not  probable  that  the  travelling  public  of  future 
generations  will  be  contented  with  a  railway  speed 
averaging  about  fifty  miles  per  hour.  At  present  the 
business  man  in  London  may  want  to  see  about  some 
business  in  Glasgow,  but  he  cannot  afford  to  spend  sixteen 
hours  in  getting  there  and  back.  While  steam  locomo- 
tives sometimes  attain  a  speed  of  eighty  miles  per  hour 
for  a  few  miles,  the  best  average,  over  a  run  of  from 
thirty  to  fifty  miles,  is  about  seventy  miles  per  hour  in 
America,  and  about  sixty  miles  in  Great  Britain. 

Already  engineers  are  turning  to  electricity  to  attain 
higher  speeds,  and  the  rate  of  the  expresses  of  the  future 
would,  no  doubt,  seem  to  us  at  present  highly  excessive,  if 
not  impossible.  Already  a  speed  of  one  hundred  and 
thirty  miles  per  hour  has  been  attained  on  trial  lines  in 
Germany,  while  one  Russian  engineer  suggests  a  scheme 
whereby  he  proposes  to  take  passengers  from  St.  Peters- 
burg to  Moscow,  a  distance  of  six  hundred  miles,  in  three 
hours'  time,  which  means  an  average  of  two  hundred  miles 
per  hour,  or  more  than  three  miles  every  minute. 

An  electric  railway  of  a  novel  character  was  shown  at 
the  Brussels  Exhibition  in  1897,  where  a  train  was 
mounted  on  a  single  rail,  supported  on  tressels,  the  rail 
standing  about  four  feet  off  the  ground.  The  railway 
cars  were  arranged  like  the  packs  on  a  mule's  back,  part 
of  the  car  hanging  down  on  either  side  of  the  central  rail, 
in  stride-leg  fashion.  A  guide-rail  ran  along  on  both 
sides  of  the  tressels  to  keep  the  car  steady.  The  train 

217 


ELECTRIC  MOTOR-CARS 

was  driven  electrically,  and  attained  a  speed  of  ninety 
miles  per  hour,  but  there  is  nothing  to  prevent  the  speed 
being  greatly  increased.  This  method  of  building  a  rail- 
way is  called  the  mono-rail  system.  We  have  already 
seen  the  electrification  of  several  important  suburban 
railways,  and  that  this  subject  is  one  to  be  reckoned  with 
in  the  near  future  is  evident  from  the  large  amount  of 
space  now  devoted  to  it  in  all  electrical  journals. 

It  is  clear  that  a  motor  placed  on  a  train  or  tramway 
car  can  be  kept  in  touch  with  the  distant  generating  station, 
but  not  so  with  motor-cars  intended  to  run  free  on  the 
public  roads.  In  this  case  it  is  necessary  for  the  motor- 
car to  carry  its  own  source  of  power  about  with  it.  This 
is  a  distinct  disadvantage.  Not  only  does  it  necessitate 
the  independent  motor-car  carrying  heavy  storage 
batteries  or  accumulators,  but  these  will  require  to  be 
constantly  recharged  with  electricity.  For  this  reason 
electric  motor-cars,  or  electro-mobiles,  are  only  convenient 
where  a  number  of  generating  stations  are  within  easy 
reach,  as  in  large  cities.  In  this  case  they  are  a  distinct 
improvement,  as  they  move  along  in  a  much  less  impul- 
sive manner  than  does  the  impatient  petrol  car.  They 
are  also  entirely  free  from  rapid  vibration  and  smell,  and 
they  are  very  easily  controlled,  as  is  clearly  demonstrated 
in  one  of  the  illustrations  in  which  a  boy  of  eight  years 
of  age  is  seen  driving  his  own  electric  motor-car.  If  it 
were  possible  to  construct  an  accumulator  of  very  large 
electrical  capacity,  and  yet  weighing  only  a  mere  fraction 
of  present  storage  batteries,  the  inventor  would  un- 
doubtedly make  a  very  great  fortune. 

The  subject  of  electric  haulage  for  canals  has  attracted 

218 


By  perm  ission  of] 


[The  Electrical  Magazine. 


An  Electric  Tractor  used  on  the  Charleroi  and  Brussels  Canal.  The  electric  motor  of  the 
tractor  receives  current  from  the  overhead  wires,  which  are  connected  to  a  dynamo  at  the 
distant  generating  station.  The  tractor  runs  on  the  ordinary  tow-pnth,  and  draws  the 
boats  through  the  canal. 


ELECTRIC  LAUNCHES 

a  good  deal  of  attention  both  in  America  and  on  the 
continent  of  Europe.  There  are  several  means  of  apply- 
ing electricity  for  this  purpose.  The  canal  boat  may  be 
supplied  with  an  electric  motor  on  board,  coupled  to  an 
ordinary  propeller,  and  the  necessary  current  led  to  the 
boat  by  a  trolley  wire  and  pole  in  the  same  manner  as  is 
done  with  an  electric  tramway  worked  on  the  overhead 
system.  This,  however,  is  not  always  convenient,  and  it 
has  been  found  that  the  wash,  caused  by  the  boat  pro- 
pelling itself,  is  very  detrimental  to  the  banks  of  the 
canal. 

A  second  plan  is  to  have  an  electric  tractor,  or  motor- 
car, on  the  ordinary  tow-path,  the  power  being  got  from 
overhead  wires.  This  system  is  at  work  in  Belgium,  and 
is  represented  in  one  of  the  illustrations,  but  it  has  been 
found  expensive  owing  to  heavy  upkeep. 

The  third  plan  is  a  modification  of  the  second  one, 
and  consists  of  an  electric  locomotive  running  on  rails 
along  the  tow-path,  the  motor  getting  its  current  by 
means  of  a  trolley  pole  and  overhead  wire.  This  plan 
is  at  work  in  the  United  States  on  the  Erie  Canal,  and 
it  is  found  that  one  of  these  electric  locomotives  can 
draw  from  three  to  six  canal  boats  at  a  speed  of  from 
four  to  six  miles  per  hour,  and  this  is  done  electrically  at 
a  smaller  cost  than  by  mules  giving  a  speed  of  one  and  a 
half  miles  per  hour. 

For  many  years  electric  launches  have  been  used  as 
pleasure-boats  on  the  River  Thames  and  elsewhere.  The 
power  is  derived  from  accumulators  placed  under  the 
seats,  and  these  work  an  electric  motor,  to  which  the 
propeller  is  coupled  direct.  The  speed  of  the  launch 

219 


NIAGARA  FALLS 

is  conveniently  regulated  by  means  of  a  switch,  in  tho 
same  manner  as  already  described  for  a  tramway  car. 
These  boats  glide  along  very  gracefully,  being  free  from 
any  smoke,  heat,  escaping  steam,  or  incessant  vibration, 
but  they  are,  of  course,  dependent  upon  some  neighbour- 
ing generating  station  to  have  their  accumulators  re- 
charged. Some  boats  carry  sufficient  power  to  take  them 
about  forty  miles  without  a  change  of  accumulators,  and 
this  distance  they  will  cover  in  seven  or  eight  hours, 
going  at  a  speed  of  from  five  to  six  miles  per  hour. 
With  the  advance  of  petrol  motors  on  board  small  boats, 
the  electric  launches  will  occupy  a  similar  position  towards 
these  that  electro-mobiles  do  as  compared  with  petrol 
motor  cars. 

Returning  to  the  generation  of  electric  power,  we  find 
some  further  points  of  interest.  Before  we  can  get 
electricity  from  the  dynamo  we  must  apply  considerable 
power  in  revolving  its  armature.  It  does  not  require 
much  force  to  spin  an  armature  round  on  its  bearings, 
but  when  the  current  is  once  set  up  in  the  coil  of  the 
armature  it  then  becomes  a  powerful  magnet,  and  is 
attracted  by  the  surrounding  magnet  in  the  opposite 
direction  to  which  we  are  rotating  it,  and  to  overcome 
this  magnetic  attraction  a  force  of  many  thousand  horse- 
power is  required,  if  the  dynamo  be  a  large  one.  As 
long  as  we  can  supply  sufficient  power  to  drive  the 
dynamo,  it  does  not  matter,  of  course,  whether  it  be 
supplied  by  an  engine,  a  water-wheel,  or  a  windmill. 
Water  power  in  great  quantities  is  not  very  general,  but 
quite  a  lot  of  waterfalls  on  the  continent  of  Europe  and 
a  few  on  this  island  are  now  harnessed.  The  great  centre 

220 


NIAGARA  FALLS 

of  interest  in  this  respect,  however,  is  in  America,  where 
they  seem  always  to  do  things  on  a  big  scale.  If  we  only 
had  a  Niagara  Falls  at  hand  in  the  centre  of  our  island 
we  should  want  no  other  source  of  energy. 

Even  the  great  flowing  river  of  Niagara  enabled  the 
early  settlers  along  its  banks  to  drive  machinery  for  saw- 
ing timber,  etc.,  but  it  is  only  during  the  last  few  years 
that  the  harnessing  of  some  of  its  vast  power  has  been 
undertaken  on  a  large  scale.  Many  generations  ago 
mechanical  engineers  must  have  looked  on  this  great 
source  of  energy  with  envy,  and  wished  that  it  were 
possible  to  convey  this  power  away  to  distant  places  of 
industry.  Electricity  makes  this  dream  a  reality.  Instead 
of  causing  the  flowing  river  to  turn  an  ordinary  water- 
wheel,  some  of  the  water  is  run  off  into  a  tunnel, 
measuring  about  twenty  feet  square.  The  river  is  about 
a  mile  in  breadth  at  this  point,  it  has  travelled  twenty 
miles  from  the  great  Lake  Erie,  and  after  making  a 
sudden  leap  over  a  precipice  of  one  hundred  and  sixty 
feet,  forming  the  great  Niagara  Falls,  it  makes  its  way 
to  Lake  Ontario.  Niagara  practically  drains  the  great 
lakes  of  the  interior,  which  have  a  total  surface  area  of 
nearly  one  hundred  thousand  square  miles.  Some  idea 
of  the  immense  volume  of  water  may  be  gained  when  we 
attempt  to  picture  eighteen  million  cubic  feet  of  water  pass- 
ing over  the  precipice  in  every  minute  of  every  day.  This 
represents  a  power  of  nine  million  horse-power,  of  which 
about  five  and  a  half  millions  are  available  for  use.  The 
total  power  of  the  works  already  constructed  and  in 
course  of  construction  will  amount  to  less  than  three- 
quarters  of  one  million,  and  yet  this  is  a  gigantic  power. 

221 


HOW  POWER  IS  DISTRIBUTED 

The  water  for  the  great  Power  Station  is  got  by  tapping 
the  river  about  one  and  a  half  miles  above  the  falls.  The 
tunnel,  already  referred  to,  is  cut  with  a  gradient  of 
thirty-six  feet  in  the  mile,  till  it  has  fallen  to  a  depth 
of  about  two  hundred  feet,  of  which  about  one  hundred 
and  forty  feet  are  available  for  use.  A  number  of  deep 
pits  are  dug  from  the  surface,  each  about  one  hundred 
and  sixty  feet  in  depth,  and  these  pits  communicate  with 
the  water  tunnel.  At  the  bottom  of  each  pit  is  placed 
a  large  water  turbine  of  five  thousand  horse-power, 
mounted  on  a  vertical  or  upright  shaft,  which  extends 
right  up  to  the  surface,  where  a  dynamo  is  fixed  to  its 
top  end.  We  have  the  turbine  or  propeller  away  down 
at  the  bottom  of  the  pit  being  rapidly  revolved  by  the 
rushing  water  in  the  tunnel,  and  on  the  top  end  of  the 
shaft  we  see  the  moving  part  of  the  dynamo  being  rapidly 
spun  round  and  generating  the  electric  current.  This 
means  a  considerable  weight  on  the  foundation  of  the 
long  upright  shaft,  but  the  pressure  of  the  water  below 
is  ingeniously  contrived  to  relieve  this. 

The  recent  extension  for  utilising  the  falls  on  the 
Canadian  side  of  the  river  will  develop  about  three 
hundred  and  seventy-five  thousand  horse-power,  which  is 
about  half  of  the  grand  total  already  referred  to.  The 
Canadian  Power  Station  will  distribute  electricity  to 
Toronto,  which  is  about  seventy-five  miles  distant.  The 
current  will  leave  the  Power  Station  at  the  immense  pres- 
sure of  sixty  thousand  volts,  and  after  reaching  Toronto 
it  will,  of  course,  be  reduced  to  working  voltages.  One 
power  station  on  the  continent  of  Europe  has  for  many 
years  successfully  distributed  power  over  a  greater  dis- 

222 


DEVELOPMENTS  AT  NIAGARA 

tance — machinery  in  Frankfort  being  driven  from  a 
generating  station  at  Lauffen,  which  is  one  hundred  miles 
distant. 

The  great  Power  Station  at  Niagara  has  caused  quite 
a  crowd  of  industries  to  spring  up  around  it.  There  are 
grain  mills,  timber  works,  paper  mills,  iron  works,  engine 
works,  and  electrical  industries  of  every  description,  all 
receiving  power  from  the  great  falls.  Large  electric 
furnaces  are  also  erected  for  producing  aluminium  from 
bauxite,  and  there  is  no  doubt  that  ere  long  the  electro- 
chemical industries  will  receive  a  great  impetus,  and  what 
are  at  present  only  possibilities  will,  by  means  of  this 
great  supply  of  electricity,  become  active  realities. 

When  a  Select  Committee  of  the  House  of  Lords 
passed  the  third  reading  of  the  Durham  (County)  Electric 
Supply  Bill,  it  was  mentioned  that  the  waste  heat  from 
the  coke  ovens  in  the  blast-furnaces  was  being  used  for 
the  production  of  electricity,  and  that  the  companies 
promoting  the  Bill  had  been  supplying  power  at  "  actually 
less  than  the  power  supplied  at  Niagara." 


223 


CHAPTER  XXII 

ELECTRICITY  IN   THE 
OBSERVATORY 

Visit  to  an  observatory — How  the  velocity  of  the  wind  is  recorded— 
Continuous  record  of  wind's  direction— Electricity  notes  time  to 
one  thousandth  of  a  second— Far  distant  earthquakes  record 
themselves  in  Great  Britain— How  the  apparatus  works— A  miss- 
ing link  in  meteorology. 

CLIMBING  the  hill  on  which  the  observatory  is 
situated  the  visitor  has  no  difficulty  in  finding  the 
building,  as  it  is  conspicuous  with  its  large  rounded 
dome,  which  serves  as  a  revolving  roof  for  the  large  tele- 
scope. At  the  side  of  the  building  one  notices  a  very 
tall  pole  on  the  top  of  which  a  little  windmill  is  spinning 
round.  If  the  visit  be  made  on  a  fresh  spring  day,  when 
a  stiff  breeze  is  blowing,  one  finds  the  little  windmill  very 
busy,  while  on  a  quiet  summer  day  it  may  be  practically 
at  a  standstill.  It  is  clear  that  the  faster  the  wind  blows 
past  the  windmill  the  quicker  it  will  revolve,  and  it  has 
been  so  arranged  that  one  kilometre  of  wind  passing  will 
cause  the  little  windmill  to  turn  round  one  thousand 
times.  If  we  can  tell  how  many  thousand  revolutions  the 
windmill  has  made  in  one  hour,  we  know  how  many 
kilometres  of  wind  have  passed  in  that  time.  As  a 
kilometre  is  a  little  more  than  half  a  mile  (about  six- 
tenths)  we  know  that  if  there  have  been  eight  thousand 

224 


VISIT  TO  AN  OBSERVATORY 

revolutions  in  an  hour  then  five  miles  of  wind  have 
passed,  and  so  we  speak  of  there  having  been  a  wind  of 
five  miles  per  hour. 

Of  course,  no  one  is  going  to  attempt  to  count  the 
thousands  of  revolutions  performed  by  the  windmill  in  an 
hour:  it  is  here  that  electricity  comes  to  the  observer's 
aid.  Two  wires  lead  down  from  the  lofty  windmill  to  the 
recording  instrument  placed  inside  the  observatory,  so 
that  the  outdoor  apparatus  can  send  signals  down  to  the 
indoor  recorder.  The  little  windmill  drives  a  train  of 
wheels,  so  geared  that  the  last  little  wheel  makes  only 
one  revolution  for  every  thousand  of  the  windmill,  and 
as  this  little  wheel  makes  an  electrical  contact,  which  is 
equivalent  to  pressing  a  bell-push,  at  the  end  of  each  of 
its  complete  revolutions,  the  recording  instrument  receives 
a  signal  which  indicates  one  thousand  revolutions  of  the 
windmill,  or  in  other  words,  the  passing  of  about  one 
half-mile  of  wind.  If  the  recorder  receives  fifty  signals 
in  one  hour,  then  the  speed  of  the  wind  is  roughly  twenty- 
five  miles  per  hour.  Each  signal  or  impulse  received 
causes  an  electro-magnet  to  move  a  pen  one  upward  step 
across  a  paper  carried  on  a  cylinder  or  drum  which  makes 
one  complete  revolution  in  twenty-four  hours.  The  paper 
is  marked  off  in  hours,  so  that  it  can  easily  be  seen  at 
a  glance  how  many  upward  moves  the  pen  has  made  in 
any  hour,  and  as  each  step  represents  one  kilometre  of 
wind,  the  speed  of  the  wind  is  readily  calculated  from  the 
French  measure  to  English  miles. 

A  storm  will  record  a  speed  of  fifty  miles  per  hour,  or 
may  even  rise  as  high  as  eighty  miles,  and  I  have  known 
the  little  windmill  to  spin  round  to  the  tune  of  ninety 
P  325 


VELOCITY  OF  WIND  RECORDED 

miles  per  hour,  but  with  a  further  increase  of  the  gale 
the  little  servant  deserted  his  lofty  post,  and  was  returned 
the  following  day  to  the  observatory  in  several  pieces, 
having  been  found  in  different  quarters  of  the  town.  By 
such  means  a  continuous  record  is  taken  of  the  velocity  of 
the  wind,  day  and  night.  Such  instruments  are  called 
anemometers,  from  the  Greek  word  anemos,  signifying 
wind,  and  metron,  measure. 

A  record  is  also  taken  electrically  of  the  direction  of 
the  wind.  A  little  vane  on  the  top  of  the  pole  points  in 
the  direction  from  which  the  wind  is  blowing,  and  it 
carries  on  it  a  spur  or  finger  which  lightly  touches  a 
number  of  little  metal  studs  placed  in  a  circle  underneath 
it.  There  are  sixteen  of  these  metal  studs  or  contact 
pieces,  from  each  of  which  a  wire  runs  down  to  the 
observatory.  These  represent  the  sixteen  cardinal  points 
of  the  compass,  North,  N.N.B.,  N.E.,  E.N.E.,  East,  and 
so  on.  The  duty  of  the  vane  is  to  telegraph  down  to  a 
recording  instrument  on  whichever  of  these  wires  it  is 
standing  over.  If  the  wind  be  due  north,  then  the  finger 
of  the  vane  rests  on  the  end  of  the  wire  arranged  to 
represent  north. 

Inside  the  observatory  the  other  ends  of  these  sixteen 
wires  are  fixed  in  the  recording  apparatus.  At  the  end 
of  every  minute  a  little  finger  or  feeler  is  made  to  sweep 
across  these  sixteen  wire-ends,  and  the  moment  it  touches 
the  end  of  the  particular  wire  with  which  the  vane  is  in 
contact  outside  the  circuit  is  completed,  the  current  from 
a  battery  finds  a  path  to  an  electro-magnet,  which  in  turn 
operates  a  pen.  This  pen  is  not  normally  in  contact 
with  the  paper,  but  when  the  magnet  receives  an  impulse 

326 


DIRECTION  OF  WIND  RECORDED 

it  draws  the  pen  sharply  against  the  cylinder,  and  as  the 
pen  is  carried  across  the  paper  along  with  the  feeler,  the 
pen  is  made  to  mark  at  the  moment  the  feeler  touches 
the  wire  upon  which  the  outdoor  vane  is  standing.  The 
paper  is,  of  course,  ruled  off  to  represent  N.,  N.N.E.,  etc. 
It  is  just  as  though  the  vane  were  supplied  with  sixteen 
different  bell-pushes,  each  representing  a  particular  point 
of  the  compass,  and  at  the  end  of  each  minute  it  pressed 
the  button  that  the  wind  caused  it  to  point  to.  By  the 
method  described  a  continuous  record  is  taken  of  the 
direction  of  the  wind  at  the  end  of  every  minute  right 
throughout  the  day  and  night. 

Climbing  up  the  stairs  in  the  tower  of  the  observatory 
till  he  reaches  the  dome,  the  visitor  finds,  during  the 
night,  the  astronomer  observing  some  phenomenon  in 
connection  with  one  of  the  planets.  The  observer  sits 
there  looking  through  a  huge  telescope,  which  he  calls  his 
equatorial  instrument.  It  points  to  the  opened  slot  of 
the  dome,  and  the  whole  telescope  is  being  very  slowly 
revolved  by  clockwork  in  the  opposite  direction  to  that 
in  which  the  earth  is  turning,  so  that  the  instrument 
remains  pointing  at  the  heavenly  body.  The  visitor 
notices  two  wires  leading  to  the  clockwork,  and  he  is 
informed  that  the  speed  of  this  motor-clock  is  electrically 
controlled  by  the  beat  of  the  standard  clock,  situated 
downstairs  in  the  observatory. 

The  observer  requires  to  read  the  position  of  his  tele- 
scope by  means  of  a  graduated  scale  marked  around  the 
axis  of  the  instrument.  The  degrees  are  so  minutely 
marked  off,  and  at  such  a  distance  from  him,  that  it  is 
necessary  to  read  them  through  a  microscope  fixed  to  the 


THE  CHRONOGRAPH 

side  of  the  telescope.  All  is  dark  in  the  dome,  and  yet 
the  observer  must  have  a  light  to  read  this  scale  by. 
A  very  tiny  electric  lamp  makes  a  useful  little  assistant 
here,  for  when  placed  close  to  the  scale  at  the  objective  of 
the  microscope,  it  illuminates  the  scale  beautifully,  and 
sheds  no  detracting  light  in  the  dome. 

Yet  another  pair  of  wires  attract  the  visitor's  attention, 
and  these  are  leading  to  something  which  the  astronomer 
holds  in  his  hand.  It  is  a  contact  maker,  which  is  the 
equivalent  of  an  ordinary  bell-push,  and  from  this  a  pair 
of  wires  lead  down  into  the  observatory,  where  a  chrono- 
graph or  time  recorder  is  at  work.  The  astronomer 
wishes  to  record  exactly  when  a  certain  phenomenon 
occurs,  so  keeping  his  eye  to  the  telescope,  he  has  merely 
to  press  the  button  of  the  push,  which  he  holds  in  his  hand, 
and  the  chronograph  downstairs  will  note  the  exact  time 
to  within  one  thousandth  of  a  second.  Before  going 
downstairs  to  see  this  chronograph,  which  is  so  called  from 
the  Greek  words  chronos,  time,  and  grapho,  I  write,  the 
visitor  remarks  that  he  is  surprised  to  find  that  the  dome 
requires  to  be  moved  round  by  hand  to  keep  the  open 
slot  opposite  the  telescope.  Having  electricity  at  hand, 
it  would  be  a  simple  matter  to  apply  a  little  motor 
to  the  wheels  of  the  dome,  and  the  motor  could  either  be 
under  the  direct  control  of  the  observer  or  it  might  at 
times  be  automatically  controlled  by  the  clock  driving  the 
telescope  round. 

Coming  down  to  the  chronograph  the  visitor  finds  it 
a  rather  clumsy  affair  after  the  small  and  compact  wind- 
recording  instruments.  There  is  a  large  cylinder  carrying 
a  sheet  of  paper  wrapped  around  it.  The  cylinder  is 

228 


ELECTRICITY  NOTES  TIME 

slowly  revolving  by  clockwork,  its  speed  being  electrically 
controlled  from  the  standard  clock.  A  pen  moves  slowly 
along  the  length  of  the  cylinder,  its  motion  being  exactly 
like  that  of  the  tympanum  and  stylus  of  a  phonograph, 
so  that  if  the  moving  pen  were  left  in  contact  with  the 
revolving  paper  it  would  mark  a  spiral  round  and  round 
the  cylinder  from  one  end  to  the  other.  The  pen  is 
normally  not  in  contact  with  the  paper,  but  at  the  end 
of  each  second  of  time  the  pen  is  made  to  strike  against 
the  paper,  making  a  small  dot.  The  pen  is  drawn 
sharply  against  the  paper  by  an  electro-magnet,  which 
receives  an  impulse  from  the  standard  clock  at  the  end 
of  each  second.  Thus  the  chronograph  paper  shows  a 
continuous  series  of  equi-distant  dots  on  the  paper,  the 
space  between  any  two  dots  representing  one  second.  The 
push  in  the  observer's  hand,  away  up  in  the  dome,  is 
connected  by  wires  to  the  electro-magnet  of  the  pen,  so 
that  he  can  also  send  an  impulse  and  make  the  pen  strike 
the  paper  at  any  desired  moment,  independent  of  the 
regular  motion  given  to  the  pen  by  the  clock.  Thus  a 
mark  will  be  made  in  between  the  two  dots  representing 
a  second.  By  means  of  a  scale  the  position  of  this  dot 
may  be  measured,  and  the  time  of  the  phenomenon  be 
correctly  found  to  the  one-thousandth  part  of  a  second. 
The  astronomer  has  wires  led  to  his  transit  telescope  and 
to  any  other  parts  of  the  observatory  from  which  he  may 
desire  to  record  the  exact  time  of  various  phenomena. 

To  obtain  an  absolutely  accurate  fraction  of  a  second 
it  is  necessary  to  take  the  "personal  equation"  into 
account,  for  some  small  fraction  of  time  must  elapse 
between  the  moment  the  observer  sees  a  star  cross  the 

229 


EARTHQUAKES  RECORDED 

spider's- web  line  in  his  transit  telescope  and  the  instant  at 
which  he  presses  the  button  of  his  push  to  make  the 
signal  to  the  chronograph.  Some  observers'  nerves  and 
muscles  will  act  quicker  than  will  others,  and  so  the 
personal  equation  of  any  observer  is  determined  by  experi- 
ment. 

One  astronomical  friend  tells  me  that  with  long  practice 
he  is  able  to  split  a  second  up  into  ten  equal  parts. 
Getting  the  beat  of  the  standard  clock  in  his  ear,  he 
can  observe  correctly  to  the  tenth  part  of  a  second,  so 
that  the  chronograph  is  only  indispensable  when  a  more 
exact  fraction  is  required,  or  when  the  observer  is  working 
at  a  point  beyond  earshot  of  his  standard  clock.  The 
chronograph  has  also  a  wide  field  of  usefulness  in  timing 
the  speed  of  projectiles,  etc. 

On  reaching  another  part  of  the  observatory,  the 
visitor  is  somewhat  surprised  to  learn  that  earthquakes 
occurring  in  all  quarters  of  the  world  are  made  to  leave 
their  record  by  means  of  a  small  instrument  in  this  room. 
Such  instruments  are  called  seismographs,  from  the  Greek 
words  seismos,  an  earthquake,  and  gi'aph,  I  write.  In 
order  to  prevent  these  being  disturbed  by  any  local  earth 
vibrations,  such  as  caused  by  trains  passing  in  the  neigh- 
bourhood, etc.,  a  deep  pit  is  dug  about  twenty  feet  down 
into  the  earth,  then  a  solid  masonry  pier  is  built  up,  and 
the  seismograph  rests  on  the  top  of  this  pier.  In  this 
way  the  instrument  is  really  resting  upon  the  solid  earth 
some  twenty  feet  down,  and  is  quite  free  from  any  surface 
disturbance. 

There  are  two  seismographs,  one  for  recording  far- 
distant  earthquakes,  and  the  other  only  replying  to  local 

230 


EARTHQUAKES   RECORDED 

ones.  The  latter  instrument  looks  the  much  more  im- 
posing of  the  two,  in  its  large  glass  case  forming  a  cube 
of  about  six  feet.  In  the  centre  of  the  case  is  a  large 
circular  glass  plate,  which  has  been  smoked  to  give  it 
a  good  black  surface  upon  which  a  pen  point  may  scratch 
a  line.  There  are  three  different  pens  resting  on  its 
surface  at  different  parts.  Each  of  these  is  connected  to 
a  different  piece  of  metal,  so  hung  on  a  stand  that  it  will 
move  with  the  slightest  change  of  level.  One  weight  is 
so  arranged  that  it  will  move  with  any  motion  from  north 
to  south,  another  records  any  motion  from  east  to  west, 
while  the  third  metal  weight  is  hung  on  spiral  springs, 
so  that  any  vertical  or  up-and-down  motion  will  be 
recorded. 

The  glass  plate  upon  which  these  pens  are  to  move 
to  and  fro  will,  of  course,  require  to  revolve  in  order  to 
take  a  record  of  the  movements.  It  would  not  be  con- 
venient to  keep  the  plate  continually  revolving,  as  local 
earthquakes  are  fortunately  few  and  far  between  in  this 
tranquil  little  island  of  ours,  and  so  it  is  necessary  that 
the  plate  be  set  in  motion  on  the  occurrence  of  an  earth- 
quake. It  is  here  that  electricity  comes  to  the  aid  of 
the  seismologist.  The  clock  for  driving  the  glass  plate 
is  left  fully  wound  up,  but  a  catch  locking  into  one  of 
the  wheels  prevents  the  clock  from  going,  so  that  the 
plate  remains  stationary.  This  little  catch  may  be  drawn 
out  of  position  by  a  small  electro-magnet,  so  that  anyone 
could  start  the  clock  by  pressing  the  button  of  a  bell- 
push  connected  to  a  battery  in  circuit.  However,  it  is 
not  the  intention  of  any  person  to  wait  on  indefinitely 
to  set  the  apparatus  in  motion  at  the  required  time; 

231 


HOW  THE  APPARATUS   WORKS 

this  must  be  done  automatically  by  the  earthquake  itself. 
In  place  of  the  ordinary  bell-push,  in  which  one  wire  is 
pressed  against  another  to  complete  the  circuit,  there  is 
a  different  arrangement  here.  The  one  wire  is  fastened 
to  a  little  piece  of  metal  in  which  a  tiny  hole  is  drilled, 
and  the  other  wire  hangs  down  freely  in  the  centre  of 
this  hole,  but  does  not  touch  the  surrounding  metal. 
This  wire  is  attached  to  the  bob  of  a  little  pendulum, 
which  will  move  with  the  slightest  change  of  level,  thus 
bringing  the  wire  in  contact  with  the  metal  attached  to 
the  other  wire.  The  first  tremor  of  an  approaching 
earthquake  is  sufficient  to  bring  about  this  contact,  which 
is  the  equivalent  of  pressing  the  button  of  the  push. 

It  is  very  important  to  be  able  to  tell  the  exact  hour 
at  which  any  earthquake  did  occur,  and  so  another  clock 
with  an  ordinary  time  dial  is  left  wound  up,  but  held  at 
twelve  o'clock  by  a  catch.  This  catch  is  released  by  the 
same  current  that  starts  the  driving  clock,  and  so  the 
time  clock  begins  to  go  at  the  first  sign  of  an  earthquake, 
and  as  the  clock  sets  off  from  twelve  oVlock  the  observer 
coming  to  the  apparatus  later  can  tell  exactly  when  the 
earthquake  occurred.  This  clock  is  placed  close  to  the 
glass  plate,  and  is  provided  with  a  little  pen,  which  makes 
a  small  mark  on  the  edge  of  the  revolving  plate  at  the 
end  of  each  second,  so  that  the  observer  can  tell  the 
exact  time  of  any  particular  movement  indicated  by 
the  traced  lines  on  the  plate.  I  have  seen  a  very  good 
record  taken  by  one  of  these  seismographs  in  Scotland 
of  an  earthquake  occurring  at  a  distance  of  two  hundred 
miles. 

The  instrument  which  records  earthquakes  happening 

232 


HOW  THE  APPARATUS  WORKS 

at  the  other  ends  of  the  earth  is  not  electrical,  and  so 
I  will  merely  mention  it  in  passing.  It  consists  of  a  very 
light  aluminium  boom  delicately  poised  in  a  horizontal 
position,  so  that  it  will  swing  from  right  to  left  by  the 
slightest  change  of  level  of  the  pier  on  which  the  apparatus 
stands.  On  the  outer  end  of  the  boom  there  is  a  thin 
aluminium  plate  or  shutter,  having  a  longitudinal  slit  in 
it,  while  the  wooden  case  enclosing  the  apparatus  has  a 
lateral  slit,  so  arranged  that  the  light  of  a  lamp  falling 
through  these  two  slits  forms  a  spot  of  light  on  the 
centre  of  a  paper  ribbon  which  is  slowly  moving  along 
by  clockwork.  This  paper  is  photographic,  so  that  it 
takes  an  impression  of  the  spot  of  light,  and  if  the  boom 
carrying  the  shutter  remains  perfectly  stationary  the  light 
will  mark  a  straight  line  up  the  centre  of  the  passing 
paper.  Any  movement  of  the  boom  to  right  or  left  will 
move  the  pencil  of  light  to  one  side  or  the  other,  and  in 
this  way  the  very  smallest  earth  movements  are  recorded. 

I  have  seen  excellent  records,  taken  in  Scotland,  of  the 
deplorable  earthquakes  that  have  occurred  in  Siberia  and 
the  more  recent  ones  in  India,  in  each  of  which  many 
thousands  of  lives  were  lost.  I  have  been  rather  surprised 
to  hear  some  men,  well  learned  in  science,  suggesting  that 
these  seismographs  would  serve  no  useful  purpose;  but 
may  we  not  hope  that  these  records  are  the  beginning  of 
a  line  of  research  which  may  ultimately  enable  men  to 
predict  seismological  disturbances  and  warn  the  inhabit- 
ants to  flee  from  a  threatened  area  ? 

Many  theories  have  been  formed  of  the  cause  of  earth- 
quakes ;  none  seem  to  appeal  to  one's  mind  as  very  satis- 
factory; but  these  seismographs  will  doubtless  aid  in 

233 


A  MISSING   LINK 

arriving  at  an  understanding  of  the  true  nature  of  these 
great  natural  disturbances  in  this  planet  of  ours. 

Man  has  already  acquired  considerable  knowledge  in 
the  prediction  of  storms,  of  wind,  and  rain,  and  yet  one 
does  not  feel  enough  confidence  in  "weather  reports"  to 
decide  emphatically  whether  to  take  an  umbrella  or  a 
walking-stick  on  one^s  daily  wanderings.  Of  course  one 
difficulty  is  that  there  is  a  great  variety  of  weather  in 
different  parts  of  the  island  at  one  time,  but  there  is  a 
factor  which  doubtless  takes  part  in  the  changes  of 
weather,  and  which  I  do  not  think  appeals  forcibly  enough 
to  the  meteorologist.  There  is  a  continual  changing  of 
the  electrical  condition  of  the  atmosphere,  and  this  must 
have  some  connection  with  other  atmospheric  changes. 

Lord  Kelvin  invented  an  apparatus  for  recording  these 
changes,  but  no  very  definite  work  seems  to  have  been 
done  with  it.  The  apparatus  requires  a  good  deal  of 
attention,  and  I  have  seen  one  of  these  instruments  go 
idle  for  months  for  lack  of  time  to  attend  to  it. 

There  exists  a  very  delicate  instrument  called  a  quad- 
rant electrometer,  which  measures  the  amount  of  charge 
of  any  electrified  body.  The  principle  is  to  compare  the 
charge  with  a  known  standard  charge,  and  the  standard  is 
got  from  a  battery  of  a  hundred  small  primary  cells.  The 
atmospheric  charge  is  obtained  by  placing  a  large  copper 
bucket  of  water  out  of  doors  on  an  insulated  stand.  If 
water  is  allowed  to  continually  drop  from  the  bucket,  the 
latter  will  become  charged  to  the  same  potential  as  the 
surrounding  atmosphere.  An  insulated  wire  leads  the 
charge  indoors  to  the  electrometer,  where  its  effect  is 
compared  with  that  of  the  standard  charge.  The  varia- 

234 


A   MISSING  LINK 

tion  of  effect  gives  movement  to  a  small  mirror  which,  by 
means  of  a  pencil  of  light,  traces  its  movements  upon  a 
photographic  paper,  and  in  this  way  a  rise  and  fall  of 
electrical  potential  is  recorded.* 

*  The  Coats  Observatory  at  Paisley  (Scotland)  contains  practically 
all  the  apparatus  described  in  this  chapter.  This  splendidly  equipped 
observatory  was  presented  to  the  town  by  some  of  the  Thread 
magnates,  whose  name  it  bears. 


235 


CHAPTER  XXIII 
ELECTRICITY  AND  THE  PHYSICIAN 

Early  exaggerated  notions  regarding  the  electric  shock — An  electric 
"  cure  "  in  the  fourth  century— Modern  quackery — Some  ways  in 
which  electricity  aids  the  physician — A  much-dreaded  disease  at 
last  overcome— Examining  the  inside  of  a  patient— An  eccentric 
heart— Other  organs  distinguishable— An  old  lady  and  a  lost 
needle — X-rays  on  the  battlefield — The  necessity  for  the  apparatus 
to  be  in  qualified  hands. 

A  soon  as  primitive  electrical  machines  had  been  con- 
structed, early  in  the  eighteenth  century,  it  became 
apparent  that  electricity  had  quite  a  startling  effect 
upon  the  human  body.  At  first  the  electric  shock  caused 
great  alarm,  as  its  magnitude  had  been  grossly  exagger- 
ated by  the  few  experimenters  who  had  experienced  it. 
One  distinguished  Dutch  scientist  declared  he  would  not 
take  a  second  shock  for  the  crown  of  France,  while  on  the 
other  hand  another  experimenter  announced  that  he  was 
willing  to  die  by  electric  shock  in  the  interests  of  science. 
Another  experimenter's  wife  after  receiving  two  shocks 
was  said  to  be  rendered  so  weak  that  she  could  not  walk, 
and  though  her  husband  had  also  suffered  great  convul- 
sions, she  tried  a  third  shock,  which  was  so  violent  as  to 
cause  bleeding  of  the  nose;  and  so  the  exaggerated  re- 
ports went  on.  As  these  early  electrical  machines  became 
less  rare,  it  soon  became  known  that  the  shocks  from 

236 


MODERN  QUACKERY 

them  were  really  not  so  dreadful  as  they  had  been 
pictured. 

The  idea  of  electricity  being  used  for  medical  purposes 
seems  to  be  very  old  indeed,  as  a  writer  living  in  the 
fourth  century  of  the  Christian  era  declares  that  "a  f reed- 
man  of  Tiberius  was  cured  of  the  gout  by  a  shock  from  a 
torpedo  fish."  I  have  no  doubt  the  cure  was  as  genuine 
as  the  many  professed  to  have  been  obtained  in  recent 
times  by  wearing  magnetic  lockets,  rings,  or  belts,  or  by 
using  "  electric  hair  brushes,"  all  of  which  must  be  placed 
under  the  category  of  quackery.  There  is  no  doubt  that 
hypochondriacal  invalids  might  receive,  through  their 
own  imaginative  powers,  more  "nerve,"  and  in  this  way 
it  has  been  possible  for  quacks  to  display  genuine  testi- 
monials. 

These  early  quackeries,  no  doubt,  made  people  some- 
what doubtful  of  the  genuine  attempts  to  use  electricity 
as  a  curative  power.  It  was  found  that  the  activity  of 
muscles,  nerves,  and  other  tissues  could  be  stimulated  by 
electric  currents,  and  some  rash  people  at  once  declared 
that  electricity  was  life  itself.  Even  to-day  one  sees  in 
quack  advertisements  such  statements  as  "Electricity  is 
Life."  It  was  claimed  by  one  experimenter  that  living 
germs  had  been  actually  formed  in  water  by  electricity, 
but  when  the  matter  was  investigated  it  was  proved  that 
the  germs  were  associated  with  some  impurities  in  the 
water,  and  when  the  experiment  was  repeated  with  dis- 
tilled water,  there  was  absolutely  no  result. 

Electricity  is  employed  by  the  physician  as  an  aid  to 
diagnosis  in  cases  of  paralysis,  etc.,  but  its  most  important 
use  lies  in  the  art  of  healing.  Until  recently  one  of  its 

237 


ELECTRICITY  AIDS   PHYSICIAN 

chief  applications  was  the  stimulating  of  muscles  into 
action,  by  which  they  might  be  kept  exercised  and  pre- 
vented from  degenerating  during  a  temporary  breakdown 
of  communications  between  the  muscle  and  the  central 
nervous  system. 

With  the  recently  acquired  knowledge  of  the  existence 
of  "invisible"  rays  and  ether  waves  of  different  kinds 
there  was  opened  up  quite  a  new  field  of  work.  It  was 
found  that  some  waves  destroyed  the  life  of  bacteria  or 
retarded  their  growth,  and  in  this  connection  may  be  men- 
tioned the  Finsen  light  treatment. 

A  Finsen  lamp  may  consist  of  an  ordinary  arc-lamp, 
the  rays  from  which  are  reflected  to  the  diseased  part, 
being  passed  through  a  lens  of  water  on  their  way  in 
order  to  obstruct  the  heat  waves.  The  beneficial  rays  are 
not  the  ordinary  light  waves,  but  those  beyond  the  visible 
spectrum,  termed  ultra-violet  light.  These  ultra-violet 
rays  are  not  only  present  in  the  arc-light,  they  are  plen- 
tiful in  sunlight,  but  the  atmosphere  readily  absorbs 
them  to  such  an  extent  that  the  arc-light  is  richer  in 
these. 

We  are  all  familiar  with  the  dreaded  disease  "tuber- 
culosis," which  when  affecting  certain  of  the  internal 
organs,  and  in  particular  the  lungs,  we  call  consumption, 
and  which,  when  appearing  externally,  attacking  the  skin 
and  underlying  tissues,  is  known  as  "  lupus."  We  are  all 
too  familiar  with  its  unpleasant  appearance  when  it 
attacks  the  nose,  mouth,  or  cheek  of  the  patient,  but  it  is 
not  necessarily  confined  to  the  face.  These  tubercular 
diseases  of  the  skin  have  long  baffled  the  physician, 
although  they  have  been  shown  to  be  due  to  specific 

238 


A  MUCH-DREADED   DISEASE 

organisms,  but  now  the  bacteria*  have  succumbed  to 
these  searching  rays.  Curiously  enough  these  same  rays 
are  most  hurtful  in  cases  of  small-pox,  and  aggravate  the 
disease  very  considerably.  In  the  case  of  lupus  these 
rays  not  only  kill  off  the  bacteria,  but  stimulate  the 
tissue,  and  thus  aid  very  materially  in  the  patient's  rapid 
recovery.  The  affected  part  has  usually  to  be  exposed  to 
the  rays  very  frequently  for  some  months,  and  while  a 
great  number  of  cases  can  be  pronounced  complete 
cures,  there  are  others  that  seem  too  far  advanced  to  be 
overcome. 

The  X-rays  have  been  found  to  operate  in  a  similar 
manner  in  cases  of  lupus,  malignant  ulcers,  etc.,  and 
sometimes  the  two  treatments  are  used  alternately. 

In  some  cases  of  even  twenty  years'*  standing,  which  had 
been  treated  by  all  other  methods,  including  the  surgeon's 
knife,  only  to  return  again,  these  searching  rays  have  com- 
pletely annihilated  the  disease.  The  results  obtained  are 
really  marvellous,  and  more  especially  so  as  the  majority 
of  the  cases  coming  for  treatment  are  those  for  whom 
there  seems  no  further  hope  of  cure  by  other  methods. 

In  addition  to  the  Finsen  light  and  X-ray  methods 
there  is  to  be  added  the  use  of  high-frequency  currents, 
such  as  are  obtained  from  large  Wimshurst  machines,  or 
more  recently  by  an  arrangement  of  induction  coils  and 
Leyden  jars.  Sometimes  one  method  is  found  to  act 


*  While  bacteria  are  termed  organisms,  it  must  be  understood  that 
they  belong  to  the  vegetable  kingdom,  just  as  fungi  do.  Some  people 
seem  to  think  of  these  microbes,  not  only  as  having  animal  life,  but  as 
possessing  a  kind  of  intelligence,  or  instinct,  by  which  they  may  make 
their  way  about  from  one  place  to  another. 

239 


SEEING  THE   HEART 

better  than  another  in  particular  cases,  and  a  change  of 
treatment  is  found  with  many  patients  beneficial.  Again 
one  method  is  sometimes  more  easily  applied  than  another 
owing  to  the  position  of  the  diseased  part,  but  it  has 
been  established  beyond  doubt  that  each  of  these  methods 
is  curative. 

Electricity  gives  the  surgeon  a  most  convenient  method 
of  cauterising  by  heating  a  fine  platinum  wire  on  passing 
a  current  of  electricity  through  it,  and  it  also  provides 
him  with  tiny  lamps  by  means  of  which  the  cavities  of 
the  body  may  be  examined. 

Apart  from  the  curative  properties  of  electricity,  the 
possibility  of  being  able  to  examine  the  "inside"  of  a 
patient  is  of  primary  importance.  A  patient  is  brought 
in  with  a  fractured  arm  or  leg,  and  the  surgeon  can  at 
once  see  what  injury  has  been  done  to  the  bones.  The 
spinal  column  and  ribs  can  be  examined,  but  the  rays  do 
more  than  distinguish  the  skeleton,  although  it  is  in  con- 
nection with  the  bones  that  the  Rontgen  rays  are  at 
present  of  chief  service.  With  properly  adjusted  tubes 
the  heart's  action  may  be  examined,  and  it  gives  one  at 
first  quite  an  eerie  feeling  to  see  a  friend's  heart  at 
work. 

In  some  of  our  large  hospitals  it  is  a  daily  occurrence 
to  have  to  fish  coins  and  other  foreign  bodies  from  the 
throats  of  children.  The  little  patient  is  placed  between 
the  X-ray  tube  and  a  fluorescent  screen,  and  in  a  moment 
the  coin  is  detected.  An  exact  description  of  its  position 
is  noted  and  handed  to  the  surgeon,  who  can  fish  it  out 
easily  with  his  "  coin-catcher." 

By  means  of  the  X-rays  and  a  fluorescent  screen  other 

240 


X-RAYS  ON   BATTLEFIELD 

organs  of  the  body  are  quite  distinguishable,  such  as  the 
lungs  and  the  liver,  and  it  is  curious  to  watch  the  move- 
ment of  the  separating  diaphragm  at  each  long  breath 
drawn  by  the  lungs. 

If  a  needle  or  any  other  foreign  body  be  accidentally 
lodged  in  the  flesh,  it  can  at  once  be  located  and  got  out 
without  unnecessary  cutting.  The  other  day  a  medical 
man  showed  me  an  X-ray  photograph  he  had  just  taken 
of  the  arm  of  an  old  lady,  who  had  met  with  an  accident. 
The  photograph  proved  that  no  injury  had  been  done  to 
the  bone,  but  it  incidentally  showed  a  needle  embedded 
in  the  arm  close  to  the  wrist,  and  probably  carried  about 
unconsciously  for  a  lifetime.  As  the  lady  was  over 
seventy  years  of  age,  and  as  there  was  no  likelihood  of 
the  needle  troubling  her  now,  the  matter  was  not  men- 
tioned to  her. 

A  specialist  finding  a  boy's  throat  giving  him  trouble 
discovered,  by  means  of  the  X-rays,  a  halfpenny  em- 
bedded in  the  throat  tissue,  the  coin  having  evidently 
been  there  for  some  considerable  time. 

It  is  difficult  to  estimate  the  great  value  of  an  X-ray 
apparatus  on  the  battlefield  for  finding  out  at  once  where 
the  bullets  or  fragments  of  shell  have  lodged  without  the 
painful  and  unsatisfactory  probing  formerly  necessary. 
One  can  remember  how  even  the  best  skill  failed  in  the 
case  of  President  Garfield,  of  the  United  States,  who  was 
shot  in  1881  by  a  disappointed  office-seeker.  Had  the 
existence  of  these  X-rays  been  then  known  there  is  little 
doubt  that  the  President  would  not  have  had  to  depart 
this  life  at  the  age  of  fifty. 

It  is  impossible  to  tell  not  only  how  much  suffering  has 
9  241 


APPARATUS  IN   QUALIFIED  HANDS 

been  avoided  but  how  many  lives  have  already  been  saved 
by  the  aid  of  Rontgen's  discovery.  The  use  of  the 
X-rays  in  taking  photographs,  or  more  particularly  for 
curative  purposes,  should  not  be  attempted  except  under 
experienced  medical  supervision,  as  too  long  exposure  or 
the  use  of  a  defective  tube  may  bring  about  serious 
"burns,"  which  in  some  cases  have  become  permanent 
sores.  Reports  of  such  occurrences  should  not,  however, 
deter  any  patient  from  submitting  himself  or  herself  to 
the  rays  under  the  guidance  of  a  competent  physician. 


243 


CHAPTER  XXIV 
ELECTRICITY  AND  RADIUM 

Exaggerated  notions  of  radium— Radium  detected  by  electricity — 
How  radium  was  discovered— Why  it  costs  so  much— How  all 
bodies,  if  sufficiently  cold,  become  phosphorescent— Radium  and 
"  shadowgraphs  "—The  physician  and  radium— The  atom  slowly 
breaking  up— May  we  ever  hope  to  transmute  the  baser  metals 
into  gold  ? — How  we  might  realise  what  a  million  really  is — How 
very  minute  quantities  of  radium  are  traced — Is  the  old  problem 
of  perpetual  motion  at  last  solved? — Radium  is  continually  pro- 
ducing electricity — How  radium  remains  at  a  higher  temperature 
than  its  surroundings — Is  all  matter  radio-active  ? 

WHEN  the  wonderful  properties  of  that  magic- 
worker    radium    were    made    known    to    the 
world    its    capabilities    soon    became    greatly 
exaggerated  and  distorted  in  the  mind  of  the  general 
public.     Its  rays  were  to  do  far  greater  wonders  in  the 
hands  of  the  physician  than  those  dealt  with  in  the  last 
chapter,  and  it  was  claimed  that  even  cancer  would  flee 
on  exposure  to  the  radium  rays. 

Some  predicted  that  radium  would  be  in  the  near 
future  a  great  source  of  motive  power  and  of  heat, 
enabling  us  to  dispense  with  the  clumsier  methods  of  the 
present  time. 

The  announcement  of  the  properties  of  radium  did  not 
come  as  such  a  surprise  to  those  interested  in  science, 
for  other  radio-active  bodies  were  already  well  known, 

243 


HOW  RADIUM   WAS  DISCOVERED 

although  not  nearly  so  active,  yet  even  among  scientists 
there  were  those  who  feared  that  the  properties  exhibited 
by  radium  would  upset  some  long-established  theories, 
such  as  the  conservation  of  energy.  It  did  not  take  long, 
however,  for  the  first  excitement  to  subside. 

In  order  to  justify  the  coupling  of  radium  and  elec- 
tricity together  in  the  title  of  this  chapter,  I  may  remark 
at  the  outset  that  but  for  electricity  it  is  doubtful  if  the 
presence  of  radium  could  ever  have  been  detected,  as  will 
be  explained  later,  and  before  the  close  of  the  chapter 
there  will  be  shown  a  very  intimate  connection  between 
radium  and  electricity. 

It  is  interesting  to  trace  how  radium  came  to  be  dis- 
covered. For  a  very  long  time  it  had  been  known  that 
certain  substances,  such  as  zinc  sulphide,  would  phos- 
phoresce in  the  dark  for  some  considerable  time  after 
being  exposed  to  light ;  and  the  general  public  have  been 
long  familiar  with  luminous  paints  as  used  on  match- 
boxes, etc. ;  uranium  salts  were  supposed  to  belong  to  the 
same  category ;  but  shortly  after  Rontgen  had  discovered 
that  his  X-rays  could  affect  a  photographic  plate,  Pro- 
fessor Becquerel,  of  Paris,  found  that  uranium  emitted 
rays  in  the  same  way ;  and  I  remember  seeing  one  of  the 
earliest  "shadowgraphs"  produced  by  exposure  to  uranium, 
about  1896.  These  rays  were  named  "Becquerel  rays,1' 
after  the  discoverer.  It  was  soon  found  that  uranium  did 
not  require  to  be  previously  exposed  to  light  in  order  to 
give  out  these  rays,  but  continued  to  be  incessantly  radio- 
active. 

A  little  later  Sir  William  Crookes,  of  London,  found 
that  the  radio-activity  was  not  really  due  so  much  to  the 

244 


WHY  IT  COSTS   SO  MUCH 

uranium  itself  as  to  some  "  impurity  "  in  the  salts.  It  was 
then  that  Madame  Curie,  wife  of  Professor  Curie,  of 
Paris  (herself  a  distinguished  chemist),  set  about  a  long 
series  of  chemical  experiments  to  try  and  locate  the  most 
radio-active  element.  Her  husband  soon  joined  her  in 
the  painstaking  search,  and  they  found  that  the  "  tail- 
ings" or  residue  of  the  ore  from  which  uranium  had 
been  extracted  proved  to  be  more  radio-active  than  the 
uranium  itself.  They  then  set  about  separating  one  con- 
stituent after  another  by  chemical  processes  (evaporation, 
crystallisation,  precipitation,  etc.),  and  they  ultimately 
found  three  distinct  elements  showing  radio-activity. 
These  the  Curies  named  radium,  polonium,  and  actinium, 
each  of  which  is  highly  radio-active,  but  while  polonium 
appears  to  be  most  active,  radium  occurs  in  the  greatest 
quantity. 

The  metal  radium  has  never  been  separated,  but  is 
found  in  combination  with  chlorine  as  radium  chloride, 
or  with  bromine  as  radium  bromide.  The  total  amount 
of  these  radio-active  bodies  found  in  pitchblende,  from 
which  they  are  extracted,  is,  according  to  Professor 
J.  J.  Thomson,  less  than  the  gold  held  in  solution  in  sea- 
water. 

As  it  would  be  necessary  to  treat  thousands  of  tons  of 
pitchblende  to  obtain  one  pound  of  radium,  it  will  be 
readily  understood  wherein  the  great  cost  of  radium 
occurs.  Of  course  the  quantities  even  of  the  compounds 
that  have  been  extracted  are  exceedingly  small;  and, 
indeed,  we  cannot  hope  that  there  will  ever  be  any  great 
accumulation  of  radium,  as  it  is  only  matter  in  a  transi- 
tory state,  probably  being  a  disintegrated  product  of 

245 


RADIUM   AND   "SHADOWGRAPHS" 

uranium,  and  during  its  own  existence  being  itself  busy 
breaking  up  into  other  forms  of  matter.  Of  course  it 
takes  a  very  long  time  to  disappear,  but  its  production  is 
probably  very  much  slower. 

Radium  chloride  looks  very  much  like  ordinary  table- 
salt,  with  a  slightly  yellowish  colour.  One  of  its  most 
striking  properties  is  the  power  of  some  of  its  rays  to 
cause  certain  chemically  prepared  screens  to  fluoresce,  just 
as  a  Rontgen-ray  apparatus  does,  but  on  a  much  smaller 
scale.  Radium  chloride  and  bromide  form  crystals  which 
are  self-luminous  in  the  dark,  but  the  "scintillations"  seen 
in  a  Crookes  spinthariscope  are  due  to  the  incessant  bom- 
bardment of  the  invisible  rays  against  a  small  fluorescent 
screen. 

It  may  incidentally  be  remarked  here  that  the  differ- 
ence between  fluorescence  and  phosphorescence  is  that  the 
former  is  only  present  as  long  as  the  exciting  rays  are 
falling  upon  the  crystals,  whereas  a  phosphorescent  body 
emits  light  for  some  considerable  time  after  exposure. 
Professor  Dewar  maintains  that  all  bodies  would  become 
phosphorescent  if  their  temperature  was  lowered  suffi- 
ciently, and  he  has  produced  phosphorescence  in  egg- 
shells, ivory,  feathers,  and  paper  when  cooled  down  to 
about  200°  below  zero  (Fahrenheit  scale)  by  means  of 
liquid  air,  the  temperature  of  which  is  another  hundred 
degrees  lower  still.  When  these  bodies  are  at  such  a  low 
temperature  and  exposed  to  light,  they  seem  to  have  the 
property  of  absorbing  energy  and  then  giving  off  light  at 
higher  temperatures. 

(  Another  property  of  radium  is  its  effect  upon  a  photo- 
graphic plate,  by  which  shadowgraphs  or  radiographs  may 

246 


PHYSICIAN  AND  RADIUM 

be  produced ;  but  as  these  had  already  been  produced  by 
X-rays  this  property  did  not  cause  so  much  wonderment. 
The  next  property  of  interest  to  the  public  is  the 
physiological  effects  of  some  of  the  radium  rays,  which 
cause  a  sore  on  any  part  of  the  body  kept  for  long  in 
proximity  to  even  the  minute  specimens  at  present  exist- 
ing, and  these  effects  are  not  immediately  apparent,  but 
develop  some  days  after  exposure.  Great  hopes  were  at 
first  entertained  that  in  the  medical  world  radium  would 
prove  of  great  value,  but  it  seems  doubtful  if  there  is  any 
different  effect  from  that  already  obtainable  from  electrical 
apparatus.  When  good  specimens  are  more  easily  ob- 
tained it  may  be  found  that  a  small  tube  of  radium  could 
get  at  some  internally  diseased  parts  to  which  at  present 
it  is  found  impossible  to  send  the  electrical  rays,  but  it  is 
necessary  to  use  great  caution  in  applying  radium  rays  to 
the  human  body. 

^  There  are  three  distinctly  different  kinds  of  rays  emitted 
by  radium,  and  for  convenience  these  have  been  dis- 
tinguished by  the  first  three  letters  of  the  Greek  alpha- 
bet— alpha,  beta,  gamma.  The  alpha  (a)  and  beta  (6) 
rays  are  exceedingly  fine  particles  of  disintegrated  matter, 
but  the  gamma  (y)  rays  are  ether  vibrations  very  similar 
to,  if  not  identical  with,  the  well-known  Rontgen  rays, 
which  we  artificially  produce  by  electrical  means.  The 
material  radiations  carry  with  them  charges  of  electricity, 
and  are  affected  by  a  neighbouring  magnet. 

v  In  addition  to  these  radiations  it  was  discovered  that 
radium  gave  off  a  radio-active  gas,  which  is  not  common 
to  all  radio-active  bodies.  This  gas  has  been  collected, 

247 


ATOM   SLOWLY  BREAKING  UP 

vaporised,  and  even  liquefied  by  the  low  temperature  of 
liquid  air. 

If  a  long  glass  tube  be  coated  with  a  chemical  substance 
which  will  become  luminous  in  the  presence  of  radio-active 
bodies,  the  passage  of  this  gas  or  "  radium  emanation " 
may  be  followed  as  it  is  sent  along  the  tube. 

It  is  supposed  that  these  emanations  are  merely  a  few 
of  the  radium  atoms  breaking  up  into  other  forms  of 
matter,  and  even  then  these  resulting  atoms  are  not 
stable,  but  also  disintegrate,  and  helium  gas  is  found  to 
be  one  resultant ;  but  as  any  other  resulting  atoms  do  not 
show  signs  of  radio-activity,  it  has  been  found  impossible 
to  follow  them.  This  disintegration  of  atoms  is  by  far 
the  most  interesting  point  in  connection  with  radium.  By 
chemical  process  or,  as  we  shall  see,  by  electrolysis  we  can 
break  up  a  molecule  of  water  into  two  atoms  of  hydrogen 
and  one  atom  of  oxygen,  but  we  can  go  no  further ;  and 
for  more  than  a  century  the  doctrine  of  Dalton  that  the 
atom  is  indivisible,  or,  as  Clerk-Maxwell  has  said,  that 
the  atoms  are  the  foundation-stones  of  the  universe,  has 
remained  our  creed.  Here,  however,  in  radium  and  other 
similar  bodies  the  atom  itself  is  breaking  up  in  the  course 
of  nature. 

The  radium  atom,  as  already  explained,  is  transformed 
by  nature  into  an  entirely  different  "  element,"  named 
helium  gas,  and  so  the  question  arises — May  we  not  yet 
hope  some  day  to  find  a  means  of  transmuting  the  baser 
metals  into  precious  gold?  At  present  we  can  neither 
produce  or  control  this  breaking  up  of  the  atom,  and  as 
Mr.  Soddy  remarked  recently,  we  may  never  hope  to 
be  able  to  transmute  silver  into  gold,  but  at  some  far 

248 


WHAT  A  MILLION  REALLY  IS 

distant  date,  if  this  disintegration  can  be  produced,  it 
might  be  found  possible  to  transform  gold  into  silver, 
which  is  of  lower  atomic  weight.  Even  if  we  could  all 
turn  our  coppers  into  golden  sovereigns  our  fortunes 
would  not  long  be  made. 

It  is  impossible  to  form  any  adequate  conception  of  the 
size  of  an  atom,  but  it  is  of  interest  to  gain  some  mental 
comparison.  With  the  microscope  we  see  tiny  objects 
which  make  no  impression  whatever  upon  the  unaided 
vision,  and  with  a  powerful  microscope  minute  objects, 
measuring  one  fifty-thousandth  part  of  an  inch,  are  made 
visible.  In  this  statement  we  have  already  got  far  beyond 
the  range  of  any  definite  comparison,  and  yet  the  very 
smallest  particle  of  matter  that  can  be  seen  by  the  most 
powerful  microscope  contains  some  eighteen  to  twenty 
millions  of  atoms,  and  again,  every  one  of  this  multitude 
comprises  at  least  a  thousand  fragments,  or,  as  Professor 
J.  J.  Thomson  terms  them,  "  corpuscles."  Who  can  form 
any  adequate  conception  of  the  size  of  a  corpuscle  ?  How 
many  million  times  a  million  must  there  be  in  a  tiny 
speck  of  water  ?  It  is  very  difficult  even  to  form  a  clear 
mental  picture  of  what  one  million  means,  and  I  would 
add  my  humble  endorsement  to  the  suggestion,  made  by 
Dr.  A.  K.  Wallace  in  Man's  Place  in  the  Universe,  that 
every  town  should  have  a  public  room  set  aside  with  one 
million  dots  clearly  shown  upon  its  walls,  so  that  the 
young  mind  might  form  some  clearer  conception  of  the 
true  magnitude  of  a  million.  To  think  of  a  million  as 
the  numeral  one  with  six  ciphers  appended  means  nothing, 
and  while  we  may  picture  a  million  as  a  thousand 
thousands,  or  as  a  hundred  groups  of  ten  thousand, 

249 


MINUTE  QUANTITIES  OP  RADIUM 

and  so  on,  I  do  not  doubt  that,  after  becoming  ac- 
customed to  a  visual  impression  of  one  million  dots  at 
one  time,  we  could  form  a  much  clearer  estimate  of  the 
magnitude  of  such  a  number.  The  wily  politician,  when 
seeking  to  impress  upon  his  constituents  the  money  being 
squandered  by  the  Government  of  the  day,  would  doubtless 
ask  them  to  visit  the  "  million  "  room,  and  then  imagine 
each  dot  to  be  a  golden  sovereign,  and,  having  formed 
that  picture,  to  multiply  it  by  so  many  hundreds  of 
duplicate  rooms,  and  so  on. 

I  have  wandered  somewhat  from  the  title  of  this 
chapter,  but  I  think  it  of  importance  that  we  should  not 
be  content  to  pass  over  any  reference  to  millions  without 
some  attempt  at  a  mental  picture  of  their  vastness.  I 
believe  it  has  been  owing  to  a  failure  of  this  kind  that 
people  claimed  for  radium  the  destruction  of  the  theory 
of  the  conservation  of  energy.  They  said,  Here  we  have 
radium  giving  out  energy,  and  without  any  loss  to  itself. 
If,  however,  one  tries  to  picture  this  energy  as  being  due 
to  the  disintegration  of  one  atom  per  second  in  a  million 
billions  of  atoms,  while  some  three  hundred  millions  of 
these  atoms  might  lie  together  in  a  row  inside  one  inch, 
then  who  can  hope  to  live  long  enough  to  observe  any 
perceptible  loss  in  its  gross  bulk  or  weight  ? 

We  need  not  fear,  therefore,  that  the  advent  of  radium 
is  going  to  upset  all  our  learning,  and  in  this  connection 
I  think  the  words  of  Sir  Oliver  Lodge  of  great  interest : 
"  A  bare  fact  is  nothing,  or  little,  till  it  is  clad  in  theory. 
Sometimes  a  fact  is  born  before  its  clothes  are  ready. 
Sometimes  a  '  layette '  has  been  provided  before  a  fact  is 
born.  Radium  is  in  the  latter  predicament.  No  fact 

250 


PERPETUAL  MOTION 

concerning  radium  need  stand  out  in  the  cold  for  lack  of 
shelter." 

It  is  interesting  to  note  how  a  minute  quantity  of 
radium  may  be  detected.  Without  going  into  the  detail 
of  the  apparatus,  it  will  be  sufficient  to  understand  that 
if  a  battery  be  connected  up  to  two  metal  plates  or  discs, 
which  are  separated  from  each  other  by  a  small  air  space, 
there  will  be  a  charge  of  electricity  upon  the  opposing 
plates,  which  will  seek  to  get  across  from  the  one  plate  to 
the  other,  but  fail  to  overcome  the  resistance  of  the  air- 
space between  them.  It  was  found  that  some  of  the  rays 
of  radium  made  the  surrounding  air  a  better  conductor  of 
electricity,  by  a  process  known  as  "  ionization,"  and 
strongly  exhibited  by  the  Rontgen  rays,  so  that  if  a  piece 
of  radium  is  brought  near  to  the  resisting  air-space,  the 
conductivity  is  so  far  improved  as  to  allow  the  discharge 
of  the  electricity  between  the  plates.  All  that  we  now 
need  is  a  sensitive  electrometer  to  indicate  the  amount  of 
charge  and  discharge  of  electricity  between  the  plates. 
This  test  is  so  very  delicate  that  I  have  seen  an  electro- 
meter indicate  a  discharge  as  soon  as  a  small  specimen  of 
radium  was  brought  into  the  room. 

I  fear  that  in  this  chapter  I  may  have  already  given 
many  details  that  are  not  of  general  interest,  and  so  in 
closing  I  will  do  no  more  than  mention  that  the  proper- 
ties of  radium  go  to  confirm  the  theory  that  the  atom  of 
matter  is  merely  the  ether  in  a  state  of  violent  motion,  or, 
as  some  prefer  to  think  of  it,  electricity  itself.  We  then 
picture  these  electrons  breaking  away  from  the  unstable 
atom  of  radium,  and,  by  the  inter-atomic  motion,  being 

251 


RADIUM   AND  ELECTRICITY 

hurled  into  space  at  an  enormous  velocity,  causing  radia- 
tion, etc. 

\  One  point  of  very  great  interest  to  the  scientific  world 
is  that  radium  keeps  giving  out  heat  perpetually  and  yet 
remains  itself  at  a  temperature  slightly  higher  than  its 
surroundings,  but  if  we  admit  an  energetic  bombardment 
of  disintegrated  particles  continually  existing  in  the  radium 
atom,  then  the  production  of  heat  due  to  such  energy  is 
quite  in  keeping  with  such  a  theory. 

In  order  to  prove  that  radium  is  continually  producing 
electricity,  a  very  ingenious  method  has  been  devised.  A 
small  amount  of  radium  is  placed  in  contact  with  a  gold- 
leaf  electroscope  inside  a  vacuum  globe,  and  the  effect  of 
the  charge  received  from  the  radium  is  that  the  two  gold 
leaves  repel  each  other,  but  when  they  have  separated  a 
certain  distance  they  come  in  contact  with  an  earth  con- 
nection, which  allows  the  electricity  to  escape  to  earth, 
and  then  fall  back  to  their  normal  position.  But  the 
leaves  are  soon  observed  to  have  again  received  a 
charge  of  electricity  from  the  radium,  and  so  the  process 
goes  on. 

Is  the  old-world  problem  of  perpetual  motion  solved  at 
last?  The  answer  must  be  in  the  negative,  for  the 
radium  will  in  long  ages  disappear,  and  possibly  long 
before  that  time  the  gold  leaves  will  have  refused  to  hold 
together  and  perform  their  arduous  task. 

Lord  Blythswood  has  recently  shown  that  if  a  piece  of 
fine  cambric,  say  from  a  handkerchief,  is  placed  in  the 
path  of  the  radium  rays,  the  fabric  of  the  cambric  shows 
signs  of  being  "  eaten  away  "  in  a  short  time. 

It  is  now  believed  that  all  matter  may  in  some  degree 

252 


I : 


MATTER  RADIO-ACTIVE 

be  radio-active,  but  if  a  stock  of  radium  will  not  have 
entirely  disappeared  at  the  end  of  ten  thousand  years, 
and  if  ordinary  matter  be  infinitely  slower  in  its  disin- 
tegration, then  there  may  easily  be  a  wholesale  breaking 
up  of  matter,  and  yet  it  may  be  far  beyond  detection 
by  man. 

Professor  Rutherford,  of  Montreal,  has  done  much  to 
fathom  the  mysteries  of  radium,  and  it  was  he  who 
suggested  the  theory  of  the  disintegration  of  the  atom. 

Doubtless  before  the  present  century  is  very  old  our 
knowledge  of  the  inner  workings  of  nature  will  be 
greatly  widened  through  the  advent  of  radium,  and  may 
help  us  to  a  better  understanding  of  electricity ;  and  our 
grandchildren  will  possibly  be  amused  to  read  of  some  of 
our  "  old-fashioned  "  ideas. 


CHAPTER  XXV 
ELECTRICITY  AND   CHEMISTRY 

What  the  escape  of  a  bubble  of  hydrogen  gas  from  a  drop  of  water 
led  to — How  electricity  affects  the  composition  of  substances — 
Ridiculous  notions  get  abroad— Humphry  Davy  finds  out  the  true 
possibilities— Electricity  extracts  new  metals  from  nature— What 
takes  place  when  a  chemical  compound  is  treated  electrically— A 
curious  reaction — Aluminium  made  marketable — How  goods  are 
electro-plated,  etc. 

TWO  Englishmen  having  received  from  Volta  a  letter 
describing  his  pile  of  metal  discs,  set  about  making 
up  a  voltaic  pile  as  already  described  in  chapter  iii. 
This  was,  of  course,  before  Volta  had  made  his  cell  or 
chemical  battery. 

These  gentlemen  used  silver  half-crown  pieces  and 
copper  discs,  separating  the  pairs  by  cloth  soaked  in 
common  salt.  They  conducted  the  electricity  by  a  wire 
to  a  metal  plate,  and  in  order  to  make  sure  that  they  had 
a  good  connection  between  the  end  of  the  wire  and  the 
plate  they  put  a  drop  of  water  on  the  plate  where  the 
end  of  the  wire  touched  it,  so  that  the  current  might  also 
find  a  path  through  the  water.  While  working  in  this 
manner,  one  of  the  experimenters  said  that  he  perceived 
the  odour  of  hydrogen  gas  coming  from  the  water,  and 
his  friend  at  the  same  time  noticed  small  bubbles  of  gas 
in  the  drop  of  water.  This  seemed  very  strange,  so  to 

254 


AN  IMPORTANT  DISCOVERY 

make  quite  sure  that  they  were  making  no  mistake,  they 
enclosed  some  water  in  a  piece  of  glass  tube  and  corked 
up  both  ends.  They  then  passed  the  end  of  the  one 
wire  from  the  voltaic  pile  through  one  cork  into  the 
water,  and  the  other  wire  through  the  second  cork,  so 
that  the  current  could  flow  in  by  the  one  wire,  through 
the  water,  and  out  by  the  other  wire  back  to  the  voltaic 
pile.  There  was  no  mistake  about  the  gas  now ;  it  could 
be  seen  bubbling  from  the  end  of  the  wire  at  which  the 
current  left  the  tube,  and  it  was  also  noticed  that  the  end 
of  the  leading-in  wire  became  tarnished  or  oxidised. 
To  prevent  this  tarnishing  they  next  used  a  piece  of 
platinum  wire  which  could  not  oxidise,  and  then  they 
found  gas  evolved  from  the  ends  of  both  wires. 

In  order  to  find  out  if  the  gases  were  the  same,  they 
arranged  the  apparatus  so  that  they  could  collect  the  gas 
from  each  wire  in  a  separate  tube,  leaving  the  current  a 
free  path  through  the  water  from  the  one  wire  to  the 
other.  They  noticed  that  the  tube  at  the  leading-in 
wire  only  filled  half  as  quickly  as  the  other,  and  on 
examination  it  was  found  that  the  gases  were  oxygen  and 
hydrogen  respectively,  there  being  twice  as  much  hydro- 
gen as  oxygen.  It  was  quite  apparent  that  the  electric 
current  was  decomposing  the  water,  which  was  already 
known  to  be  composed  of  two  parts  of  hydrogen  to  one 
of  oxygen,  or  as  the  chemist  would  indicate  it  in  symbols, 
H20. 

Here  we  have  a  good  example  of  how  much  may 
depend  upon  the  quick  observation  of  an  experimenter. 
These  two  gentlemen — Mr.  Nicholson  and  Sir  Anthony 
Carlisle — were  not  looking  for  any  effect  of  the  current  in 

2SS 


RIDICULOUS  NOTIONS 

the  water,  which  was  merely  used  to  make  a  convenient 
and  sure  connection  between  the  wire  and  the  metal  plate 
through  which  they  wished  to  pass  the  current.  The 
odour  of  hydrogen  evolved  from  such  a  small  quantity  of 
water  might  easily  have  passed  unnoticed,  and  we  might 
not  have  been  to-day  so  far  forward  in  one  of  the  com- 
mercial adaptations  of  electricity. 

The  effect  of  the  current  on  other  liquids  was  soon  tried, 
and  it  was  found  that  oxygen  and  the  acids  always 
collected  at  the  leading-in  wire,  whereas  hydrogen,  metals, 
and  alkalies  (potash,  soda,  etc.),  always  gathered  at  the 
end  of  the  wire  at  which  the  current  left. 

Sir  Humphry  Davy,  who  would  only  be  about  twelve 
years  of  age  at  this  time  (1800),  was  led,  at  a  later  date, 
to  wonder  whether  there  would  be  any  effect  if  the  wires 
were  put  into  two  separate  vessels  containing  water, 
instead  of  both  dipping  into  the  one  vessel.  He  tried 
this  and  found  no  result,  but  he  happened  to  put  the 
fingers  of  one  hand  into  the  water  in  one  vessel  while  his 
other  hand  was  in  contact  with  the  water  in  the  second 
vessel,  and  at  this  moment  he  noticed  gas  evolved  from 
both  wires  in  their  separate  vessels.  This  seemed  a  most 
unaccountable  result,  so  Davy  got  three  friends  to  stand 
hand-in-hand  and  form  a  chain,  and  he  found  that  when- 
ever the  two  friends  at  the  ends  of  the  chain  put  their 
fingers  into  the  glass  vessels  the  gases  were  immediately 
given  off  in  the  water  at  the  ends  of  the  wires. 

It  was  in  following  up  these  experiments  and  some 
others  regarding  the  heat  effect  of  the  current  that  Davy 
first  produced  the  electric  arc  between  two  carbon  points. 
People  began  to  talk  and  write  a  great  deal  of  nonsense 

256 


SIR  HUMPHRY  DAVY 

about  what  the  electric  current  could  do.  Some  experi- 
menters went  the  length  of  claiming  that  by  passing  an 
electric  current  through  water  they  had  been  able  to 
produce  certain  chemical  compounds,  no  trace  of  which 
was  previously  in  the  water,  as  it  had  been  carefully 
distilled. 

Humphry  Davy  would  doubtless  be  annoyed  that  any 
such  ridiculous  statements  should  get  about,  so  he  began 
a  series  of  very  exhaustive  experiments  to  see  what  could 
really  be  done  by  the  electric  current  passing  through 
different  substances.  How  much  we  really  owe  to  these 
experiments  it  is  difficult  to  realise.  In  one  experiment, 
by  passing  the  current  through  some  potash  (potassium 
oxide),  which  he  had  heated  till  it  became  liquid,  Davy 
found  oxygen  gas  given  off,  and  he  saw  small  metallic 
globules  appear  in  the  liquid,  which  metal  was  afterwards 
named  potassium.  From  soda  he  produced  the  metal 
sodium,  from  lime  came  calcium,  from  an  earth  known  as 
alumina  he  got  the  metal  aluminium,  and  so  on.  To-day 
we  have  vast  industries  built  up  on  these  early  experi- 
ments made  by  Davy. 

Before  glancing  at  the  work  done  by  electricity  going 
hand-in-hand  with  chemistry  in  the  industrial  world,  it 
may  be  of  interest  to  form  some  idea  of  what  takes  place 
in  the  liquid  when  the  current  passes  through  it.  We 
must  picture  every  material  thing  as  made  up  of  tiny 
molecules,  and  each  of  these  again  composed  of  various 
groupings  of  the  atoms  of  simpler  bodies.  We  have 
already  referred  to  the  water  molecule  as  being  composed 
of  two  atoms  of  hydrogen  to  one  of  oxygen,  and  we  may 
picture  these  three  atoms  holding  on  to  each  other,  while 
R  257 


ELECTRICITY  EXTRACTS   METALS 

we  may  further  consider  this  apparent  attraction  to  be 
due  to  a  vibratory  movement  in  the  atoms,  or  the 
temperature  of  the  atoms.  Whatever  it  may  be  that 
binds  together  the  atoms,  it  is  disturbed  by  the  passage 
of  an  electric  current,  and  we  find  the  two  hydrogen 
atoms  breaking  away  from  their  former  companion  the 
oxygen  atom,  and  congregating  at  the  wire  leading  the 
current  out,  while  the  freed  oxygen  atoms  make  their 
rendezvous  the  point  where  the  current  enters. 

If  we  take  hydrochloric  acid  and  pass  an  eleck'ic  current 
through  it,  we  find  an  equal  quantity  of  hydrogen  and 
chlorine  gas  at  the  respective  wire  ends  or  "electrodes," 
and  this  is  just  what  one  would  predict,  as  the  molecule  of 
hydrochloric  acid  is  composed  of  one  atom  of  hydrogen 
and  one  atom  of  chlorine  gas. 

This  electric  analysis  was  named  electrolysis  (electro 
and  Greek  lysis,  a  loosing)  by  Faraday,  who  did  so  much 
for  this  and  other  departments  of  science,  and  to-day  we 
have  many  commercial  adaptations  of  the  electrolytic 
process.  In  the  great  alkali  manufacture,  common  salt 
(sodium  chloride)  is  electrolysed  into  sodium  and  chlorine. 
When  the  sodium  is  brought  into  contact  with  water 
and  steam  it  becomes  caustic  soda  (sodium  hydrate), 
or  if  carbonic  acid  gas  is  injected  into  the  apparatus 
we  get  carbonate  of  soda,  while  the  chlorine  is  used 
directly  in  the  production  of  bleaching  powder  (chloride 
of  lime). 

The  chemical  effect  of  the  electric  current  is  also  used 
in  connection  with  the  rectification  of  alcohol,  the 
purification  of  sewage,  the  extraction  of  gold  from  the 
refuse  or  "tailings,"  but  perhaps  the  most  interesting  is 


ALUMINIUM  MADE  MARKETABLE 

the  production  of  the  metal  aluminium  briefly  referred 
to  in  chapter  xxvii.  As  stated  in  that  chapter,  the  pro- 
duction of  aluminium  is  not  directly  due  to  the  heat- 
ing effect  of  the  electric  furnace,  but  to  chemical  changes 
brought  about  by  the  effect  of  the  current,  which  changes 
can  only  take  place  at  a  high  temperature. 

The  production  of  aluminium  by  the  electrolytic  process 
is  of  particular  interest,  as  without  this  means  we  could 
not  have  aluminium  at  a  marketable  price.  Previous 
to  the  use  of  electric  methods  aluminium  cost  one  pound 
sterling  per  pound  weight,  whereas  the  same  quantity  may 
now  be  bought  for  one  shilling. 

It  is  interesting  to  note  that  when  we  decompose  water 
by  the  passage  of  an  electric  current,  and  we  have  the 
one  platinum  wire  end  or  electrode  with  its  evolved 
hydrogen  gas  and  the  second  electrode  with  its  accumula- 
tion of  oxygen  gas,  there  is  a  very  strange  thing  that 
happens.  If  we  take  away  the  battery  and  connect  the 
two  wires  from  the  tube  together  to  form  a  direct  circuit 
from  the  one  electrode  to  the  other,  we  immediately  get  a 
current  of  electricity  flowing  through  this  wire  from  the 
tube  of  oxygen  to  the  tube  of  hydrogen,  and  through  the 
water  from  the  latter  to  the  former,  making  a  complete 
circuit.  We  first  of  all  passed  a  current  of  electricity 
through  the  water,  causing  chemical  disturbances,  and 
now  we  find  that  these  altered  chemical  conditions  will 
set  up  a  similar  current  when  working  back  to  their 
previous  positions. 

In  the  foregoing  experiment  we  have  the  basis  of  the 
storage  cell  or  accumulator.  When  referring  to  the 
action  of  these  secondary  batteries  in  chapter  iii.,  in  order 

259 


GOODS   ELECTRO-PLATED 

to  explain  the  charging  and  discharging,  I  used  as  an 
analogy  a  grandfather's  clock,  in  which  we  expended 
energy  in  raising  the  weights,  and  these  in  falling  back 
again  did  useful  work  but  soon  expended  the  potential 
energy  given  them.  We  raised  the  weights,  they 
travelled  back  in  the  opposite  direction,  and  in  the 
secondary  battery  or  in  the  electro-decomposition  of 
water  the  current  comes  out  of  the  apparatus  in  the 
opposite  direction  to  which  we  put  it  in,  just  as  when  we 
wind  a  spring  which,  in  returning  to  normal,  exerts  energy 
in  the  opposite  direction. 

In  connection  with  the  electrolysis  of  water  some 
physicists  maintain  that  the  decomposition  is  due  to 
secondary  action  dependent  on  the  presence  of  acids  or 
salts  in  the  water.  Others  suggest  that  the  presence  of 
these  merely  reduces  the  electrical  conductivity  of  the 
liquid.  In  any  case  it  is  possible  to  decompose  ordinary 
water  without  the  addition  of  acids. 

After  Sir  Humphry  Davy  had  made  known  his 
electrolytic  discoveries,  no  doubt  many  chemists  would 
begin  experimenting  with  the  electric  current,  and  it  is 
not  surprising  that  several  independent  workers  claimed 
to  have  discovered  that  when  the  current  was  passed 
through  a  liquid  containing  some  metal  in  solution,  such 
as  copper  sulphate,  the  metal  was  deposited  on  the  end 
of  the  wire  from  which  the  current  left  the  solution.  A 
Birmingham  surgeon  found  that  if  he  attached  a  metal 
object  to  the  leading-out  wire  this  article  became  coated 
with  the  metal  that  was  held  in  the  solution.  It  was 
evident  that  the  electric  current  was  causing  the  mole- 
cules of  the  solution  to  break  up  and  the  atoms  of  the 

260 


ELECTROTYPING 

metal  were  gathering  at  the  leading-out  wire.  The 
current  would  soon  free  all  the  metal  atoms  in  the 
solution,  so  it  was  found  necessary  to  supply  further 
metal  to  the  solution,  and  this  was  done  by  attaching  a 
piece  of  the  metal  to  the  leading-in  wire.  If  the  solution 
used  was  a  double  cyanide  of  silver,  and  a  piece  of  silver 
metal  was  attached  to  the  leading-in  wire,  then  a  metal 
object  suspended  in  the  liquid  from  the  leading-out  wire 
would  become  covered  with  metallic  silver,  and  in  this 
way  the  great  industry  of  electro-plating  was  founded. 
We  have  silver-plated,  gold-plated,  or  nickel-plated 
goods,  in  which  we  have  given  some  baser  metal  a  real 
coat  of  these  more  valuable  ones. 

The  object  to  be  covered  need  not  itself  be  made  of 
metal  as  long  as  a  conducting  surface  is  given  to  it 
whereby  the  current  may  pass  over  the  article.  A  mould 
of  any  object  made  in  wax  and  covered  with  plumbago 
may  be  placed  in  a  solution  of  copper  sulphate,  and  a 
coat  of  copper  electrically  produced  as  just  described. 
In  this  we  have  the  basis  of  electrotyping,  for  if  we  take 
an  engraved  block  and  make  a  mould  from  it  we  can 
deposit  a  metal  film  over  it,  and  then  removing  the 
mould  we  may  back  the  film  up  with  metallic  alloys  for 
the  sake  of  cheapness,  or  we  may  make  the  electrotype  in 
solid  copper,  so  that  we  then  have  a  second  block  corre- 
sponding to  the  original  engraved  one. 

Electrotyping  is  practically  electroplating,  but  the 
former  term  is  used  to  denote  that  the  coating  produced 
is  removed  and  then  filled  in  with  an  alloy,  whereas  in 
electro-plating  we  merely  add  a  permanent  coating  of  a 
rarer  metal  to  the  object  treated.  This  is,  of  course,  of 

261 


ELECTROLYTIC  PROCESS 

great  service  in  connection  with  newspapers,  illustrated 
magazines,  and  books. 

A  plaster-of- Paris  bust  may  be  electrically  covered  with 
metal,  and  even  natural  objects,  such  as  leaves,  insects, 
etc.,  may  be  faithfully  reproduced  in  every  detail  by 
electro-deposition. 

As  the  metal  deposited  is  always  pure  we  have  here  a 
means  of  producing  pure  copper,  the  production  of  which, 
by  the  electrolytic  process,  has  now  become  a  great 
industry. 

To  get  the  best  effect  in  all  electrolytic  operations  we 
require  a  large  amount  of  current  at  a  low  pressure,  and 
dynamos  are  now  specially  constructed  for  this  purpose ; 
but  batteries  may,  of  course,  be  used  for  experimental  or 
small  work. 

If  the  two  experimenters  who  first  noticed  the  escape 
of  hydrogen  gas  from  a  drop  of  water  through  which  an 
electric  current  was  passing  had  predicted  that  their 
simple  discovery  would  lead  to  the  creation  of  enormous 
industries  employing  thousands  of  workers,  their  claims 
would  certainly  have  been  discredited,  but  to-day  these 
great  industries  do  exist. 


362 


CHAPTER  XXVI 
ELECTRICITY  IN  THE   COAL-MINE 

Edward  I.  prohibits  the  use  of  coal— Early  ideas  of  getting  at  the 
coal— First  attempts  in  using  machinery  underground— A  trip 
down  a  coal-pit — Electric  light  and  haulage  underground — The 
employment  of  ponies  underground — Electric  coal-cutters  at  work 
— Men  go  with  a  powerful  machine  along  a  narrow  passage  only 
eighteen  inches  in  height — Is  the  miner  deprived  of  employment 
by  labour-saving  machinery  ?  — The  application  of  electricity 
enables  old  mines  to  be  reopened  and  worked  at  a  profit. 

WE  are  all  very  familiar  with  that  mineralised 
vegetable  matter  to  which  we  give  the  name 
of  coal,  and  no  one  needs  to  be  informed  that 
it  is  found  embedded  in  the  earth  in  large  layers  or  seams, 
but  a  few  introductory  remarks  may  be  of  interest. 

Although  the  ancients  knew  of  the  existence  of  coal 
and  were  aware  that  it  would  burn,  they  did  not  seek  to 
make  any  practical  use  of  it,  as  there  was  plenty  of  wood 
to  be  much  more  easily  obtained. 

The  introduction  of  coal,  or  as  it  was  at  first  called  by 
Londoners,  sea-coal,  because  it  came  to  them  by  the  sea, 
met  with  great  opposition.  A  few  years  before  the 
Battle  of  Bannockburn  we  find  Parliament  successfully 
petitioning  King  Edward  I.  to  prohibit  the  use  of  coal  in 
London  as  the  citizens  were  offended  at  the  "sulferous 
smoke  and  savor  of  the  firing,"  and  at  a  later  date  we 

263 


EARLY  IDEAS  OF  GETTING  COAL 

find  that  "  the  nice  dames  of  London  would  not  come 
into  any  house  or  room  where  sea-coals  were  burned."' 

With  the  increase  of  industries,  such  as  iron -smelting, 
it  became  almost  a  necessity  to  make  use  of  coal,  as  the 
country's  forests  were  quickly  disappearing.  One  quota- 
tion, from  an  interesting  tract  written  in  1629.  will  serve 
to  show  how  the  matter  then  stood.  An  ironmaster  in 
the  neighbourhood  of  Durham  is  accused  of  having 
"brought  to  the  ground  above  30,000  oaks  in  his  life- 
time ;  and  if  he  live  long  enough  it  is  doubted  if  he  will 
leave  so  much  timber  in  the  whole  country  as  will  repair 
one  of  our  churches  if  it  should  fall."  It  was  not.  how- 
ever, until  the  eighteenth  century  that  coal  came  to  be 
used  in  iron-smelting. 

The  invention  of  the  steam-engine  gave  a  great  natural 
impulse  to  the  use  of  coal,  for  it  not  only  became  a  large 
consumer,  but  it  also  made  the  "  winning v/  of  coal  from 
the  bowels  of  the  earth  a  much  easier  task. 

The  first  idea  of  obtaining  coal  was  to  open  up  the 
ground  as  is  done  in  a  stone  quarry :  then  followed  a 
system  of  tunnelling  into  the  bottom  of  a  hill  in  which 
seams  of  coal  were  known  to  exist.  Obtained  in  this  way 
the  early  coals  would  be  of  inferior  quality,  being  taken 
from  near  the  surface,  so  that  the  "  stench  "  complained  of 
may  have  been  greater  than  the  smoke  to  which  we  are 
now  accustomed. 

It  was  soon  found  that  the  best  seams  of  coal  were 
buried  too  deep  in  the  earth  to  be  got  at  by  the  opening 
up  of  the  ground,  and  there  was  nothing  for  it  but  to  dig 
a  deep  hole  or  pit  down  which  men  might  be  lowered  into 
the  earth.  Mines  have  been  sunk  as  deep  as  3,490  feet, 

264 


By  permission  of 


Siemens  Schukert  Werke. 


I.     A    HIGH-SPEED   ELECTRIC  TRAIN 


The  electric  motor  may  be  placed  below  the  passenger  car  and  directly  coupled  to  the  axles. 
Electric  cars  built  upon  this  plan  have  attained  a  speed  of  130  miles  per  hour. 

2.     AN    ELECTRIC   TRAIN    IN    A   COAL   MINE 

By  means  of  electricity  power  can  be  conveyed  into  mines  to  electric  locomotives,  which  are 
thus  driven  by  the  dynamos  situated  above  ground. 


TRIP  DOWN  A  COAL-PIT 

or  considerably  over  half  a  mile  down  below  the  surface. 
The  seams  vary  from  a  few  inches  to  more  than  thirty  feet 
in  thickness.  Coming  to  a  seam  of  coal,  it  is  the  duty  of 
the  miner  to  cut  away  the  "  black  diamond "  and  send  it 
to  the  surface,  and  it  is  in  connection  with  the  cutting  of 
the  coal  that  electricity  is  already  playing  a  most  im- 
portant part. 

Till  quite  recently  it  has  been  necessary  to  do  all  the 
hard  work  by  manual  labour,  because  of  the  difficulty  of 
carrying  energy  to  any  mechanical  appliances  deep  down 
in  a  mine.  Attempts  were  at  first  made  with  long  con- 
necting rods  or  shafts  from  an  engine  on  the  surface, 
reaching  down  to  the  bottom  of  the  pit.  In  some  cases 
even  engines  and  boilers  were  placed  away  down  in  the 
earth,  more  recently  compressed  air  was  used,  and  is  still 
in  use ;  but  what  a  stride  we  have  now  made  in  being  able 
to  carry  electrical  energy  from  the  surface  along  a 
stationary  wire,  away  down  into  the  mine,  and  into  the 
most  awkward  coal  seams,  there  to  drive  a  motor  attached 
to  a  machine. 

As  it  is  not  convenient  for  everyone  to  visit  a  coal- 
mine, it  may  be  of  interest  to  give  a  brief  description  of 
the  different  ways  in  which  we  find  electricity  serving  the 
miner. 

Having  gone  by  train  into  the  country,  the  visitor 
makes  his  way  to  the  pit-head,  where  he  finds  an  engine- 
house  in  which  an  engine  is  driving  a  dynamo  and  generat- 
ing current.  He  first  of  all  notices  a  cable  stretching 
from  the  engine-house  away  across  the  fields,  and  he 
learns  that  this  cable  is  conducting  current  to  an  electric 
motor,  placed  on  a  river  bank,  about  a  mile  distant,  and 

265 


TRIP  DOWN  A  COAL-PIT 

that  the  motor  is  there  driving  a  pump  which,  in  turn,  is 
forcing  water  from  the  river  through  a  pipe  to  the 
engine-house.  Instead  of  having  a  small  engine  and 
boiler  at  the  river  with  someone  in  attendance,  this  little 
motor,  quite  unattended,  is  under  entire  control  from  the 
distant  engine-house. 

In  a  separate  building  the  visitor  finds  another  engine, 
or  it  may  be  an  electro-motor,  for  raising  and  lowering 
the  cages  in  the  pit-shaft,  and  if  he  is  of  nervous  tempera- 
ment he  may  drop  a  hint  to  the  engine-driver  that  he 
has  no  desire  to  feel  the  sensation  of  flying  down  the  pit- 
shaft  at  full  speed.  Getting  on  to  the  cage,  the  novice  is 
warned  by  the  manager  to  take  a  good  grip  of  the  iron 
bar  overhead,  and  as  soon  as  he  is  plunged  into  darkness 
he  is  rather  alarmed,  if  it  be  his  first  experience,  to  hear 
a  sudden  deafening  clatter  immediately  overhead,  which 
he  is  informed  is  caused  by  the  "  policeman,1'  this  name 
being  given  to  a  very  heavy  trap-door  which  falls  over  the 
pit  mouth  as  soon  as  the  cage  enters  the  shaft.  It  seems 
a  long  journey  to  the  pit  bottom,  but  the  engine-driver  is 
putting  the  stranger  down  more  cautiously  than  he  does 
the  experienced  miner.  If  the  pit  be  one  of  2,000  feet 
in  depth,  the  visitor  welcomes  the  bump  which  assures 
him  he  is  at  the  end  of  his  downward  journey. 

If  the  explorer  has  expected  to  find  himself  in  a  large 
spacious  underground  coal  quarry,  he  is  disappointed. 
Even  if  the  mine  be  an  important  one,  there  is  no  more 
open  space  in  the  pit  bottom  than  one  finds  in  a  large 
room,  and  from  this  space  a  number  of  tunnels  or  roads 
lead  off  in  different  directions.  The  coal  here  has  not 
been  touched,  except  to  make  these  passages  through  it, 

266 


ELECTRIC  LIGHT  UNDERGROUND 

for  it  is  necessary  to  leave  the  earth  as  solid  as  possible 
all  around  the  pit-shaft.  No  matter  how  valuable  the 
coal  seams  may  be,  the  miners  must  travel  two  or  three 
hundred  feet  along  these  main  roads  before  they  touch 
any  coal.* 

Before  setting  off  to  explore  the  mine  the  visitor  is 
attracted  by  the  noise  of  machinery,  and  in  this  particular 
mine  he  has  no  difficulty  in  finding  his  way  about,  as  the 
bottom  and  the  main  roads  are  equipped  with  incandescent 
electric  lamps,  connected  to  the  dynamo  aboveground. 
He  finds  the  noise  to  come  from  a  room  close  to  the 
pit  bottom,  where  an  electro-motor,  also  connected  with 
the  dynamo  aboveground,  is  driving  a  number  of  large 
drums,  each  of  which  is  hauling  in  or  paying  off  a  long 
wire  rope.  Each  of  these  haulage  ropes  passes  right 
along  one  of  the  main  roads,  lying  between  the  rails  of 
a  narrow-gauge  track,  so  that  the  little  trucks,  called 
"hutches'"  or  "tubs,"  may  be  hauled  to  the  pit  bottom 
and  then  sent  up  the  shaft  to  be  unloaded. 

The  motor-man  has  a  series  of  electric  bells  of  different 
sounds,  each  one  representing  a  different  road,  and  as  two 
bare  wires  are  led  along  the  roof  of  each  main  road, 
the  miner  can  make  the  wires  touch  each  other  at  any 
place,  and  thus  signal  to  the  motor-man  to  haul  in  his 
train-load  of  coals.  Touching  the  wires  together  is 
equivalent  to  pressing  a  bell-push. 

In  this  case  the  electro-motor  is  stationary,  and  merely 
hauls  in  the  wire  rope,  thus  propelling  the  hutches,  but  in 

*  The  descriptions  refer  to  the  working  of  a  mine  on  what  is  called 
the  longwall  system,  consecutive  slices  being  taken  off  the  whole 
face  of  the  seam. 

267 


HAULAGE  UNDERGROUND 

some  mines,  such  as  American  drift  mines,  where  an  in- 
clined tunnel  is  run  into  the  mine  instead  of  a  perpen- 
dicular shaft,  the  motor  may  be  carried  on  a  small  truck, 
thus  forming  a  miniature  locomotive,  and  receiving  power 
from  a  fixed  conductor  overhead,  just  as  an  electric  tram- 
way car  does. 

Ponies  are  still  used  underground  for  hauling  the 
hutches  along  the  side  or  branch  roads  to  the  main  roads, 
and  at  present  it  looks  as  though  these  could  not  very 
conveniently  be  replaced  even  by  electricity;  but  it  is 
quite  a  mistaken  idea  to  suppose  that  these  ponies  are 
blind  or  that  they  are  in  any  way  ill-used.  My  ex- 
perience on  visiting  mines,  where  sometimes  as  many  as 
thirty  ponies  are  at  work  in  one  pit,  has  been  to  find  the 
animals  in  excellent  health,  well  cared  for,  and  most 
kindly  treated,  and  I  have  seen  nothing  to  indicate  that 
any  of  these  ponies  had  a  grievance. 

The  inexperienced  sightseer  may  make  his  way  along 
one  of  the  main  roads  expecting  to  come  upon  a  large 
space  with  a  crowd  of  miners  all  together  clearing  it  of 
coal,  but  such  expectations  will  not  be  fulfilled,  for  he 
will  find  nothing  but  a  series  of  roads  or  tunnels. 

When  the  visitor  gets  away  from  the  main  road  he 
finds  he  can  no  longer  stand  upright,  but  has  to  walk 
along  with  his  body  bent  at  right  angles,  and  even  then  his 
guide  will  warn  him  occasionally  to  watch  his  head,  or 
to  be  careful  not  to  touch  the  roof  at  some  particular 
place  as  it  is  "just  hanging."  As  he  walks  along,  guided 
by  the  light  of  a  small  lamp,  the  visitor  notices  some 
cables  hung  up  in  a  very  temporary  fashion  on  the  walls 
of  the  road  or  from  the  roof,  and  he  learns  that  these  are 

26$ 


ELECTRIC   COAL-CUTTERS 

conveying  electricity  to  the  coal-cutting  machines.  He 
need  not  ask  why  the  cables  are  so  loosely  tied  up,  for 
he  soon  comes  upon  a  "fall,"  where  the  roof  has  come  down 
and  almost  blocked  the  whole  road,  leaving  the  visitor 
to  climb  through  a  space  that  is  only  entitled  to  be 
called  a  hole.  Here  the  cables  have  come  down  with  the 
roof,  but  being  slack  and  only  insecurely  fastened  they 
have  offered  no  resistance  to  the  fall,  so  that  no  damage 
has  been  done.  The  fall  will  soon  be  cleared  away,  and 
wooden  props  put  in  to  secure  the  roof.  In  some  mines 
where  there  are  bad  roofs  one  finds  in  these  roads  whole 
regiments  of  wooden  props,  which  continually  require 
renewal,  as  they  give  way  under  the  great  pressure. 

From  this  side  road,  which  the  visitor  has  been  walk- 
ing along,  there  are  a  dozen  narrow  passages  branching 
oft'  at  right  angles  to  it,  but  there  is  no  sign  of  coal- 
cutting  yet.  These  twelve  roads,  about  sixteen  yards 
apart,  lead  up  to  the  coal  seam.  This  seam,  which  could 
originally  be  seen  along  the  wall  of  the  side  road,  has 
had  a  number  of  slices  cut  off  its  whole  length,  and  as 
each  slice  was  taken  out  the  cavity  was  filled  in  with 
stone  rubbish  taken  from  these  passages,  their  roofs 
being  cut  away  to  give  the  miners  room  to  draw  in  the 
hutches  or  trucks  and  get  the  coal  away. 

The  visitor  enters  one  of  these  twelve  passages,  being 
informed  that  he  is  in  road  No.  8,  and  as  this  seam  has  been 
worked  for  some  time,  he  finds  he  has  quite  a  long  way 
to  travel  in  a  very  cramped  position,  for  it  is  difficult  to 
avoid  touching  the  roof  with  his  back.  On  reaching  the 
end  of  this  road  he  comes  to  what  at  first  appears  to  be 
a  dead  end,  and  as  he  has  come  during  the  night-time  in 

269 


ELECTRIC  COAL-CUTTERS 

order  to  see  the  electrical  coal-cutters  at  work  he  finds 
no  one  in  this  road  at  all.  He  soon  hears  the  hum  of 
machinery  in  the  distance,  and  on  taking  his  lamp  to 
the  apparent  dead  end  he  finds  a  narrow  passage  only 
eighteen  inches  in  height  and  four  feet  wide  running  right 
past  the  end  of  his  road. 

If  the  visitor  cares  to  crawl  or  "  worm  "  his  way  along 
this  narrow  passage,  he  will  soon  come  on  the  end  of 
No.  7  road,  and  then  a  little  further  on  the  end  of 
No.  6  road,  and  so  on,  all  these  roads  leading  up  to  the 
face  of  this  same  seam,  but  as  the  noise  of  machinery  is 
drawing  nearer,  and  as  everywhere  it  is  pitch  dark,  he 
prefers  to  crawl  back  to  the  entrance  of  his  road.  Very 
soon  he  hears  two  men  calling  to  each  other  occasionally 
over  the  hum  of  the  machinery,  and  in  a  little  he  dis- 
cerns a  miner  coming  creeping  along  this  narrow  passage 
with  a  pick  and  shovel,  clearing  the  way  for  the  electric 
coal-cutter.  It  is  no  easy  task  to  use  a  pick  and  shovel 
while  lying  flat  down  with  only  eighteen  inches  between  the 
floor  and  the  roof,  just  about  the  space  below  an  ordinary 
chair  seat.  Close  behind  this  man  comes  the  coal-cutting 
machine,  sliding  along  on  skids,  and  as  the  machine 
practically  fills  the  whole  space,  the  visitor  cannot  get 
a  view  of  it  till  it  comes  opposite  the  end  of  his  road. 
(It  is  in  this  position  that  the  accompanying  photograph 
was  taken.) 

When  the  machine  comes  within  sight  and  passes 
the  end  of  his  road,  the  visitor  finds  it  is  drawing 
itself  along  by  means  of  a  haulage  rope,  which  is  fixed  at 
some  distance  along  the  passage,  and  is  being  gradually 
wound  on  to  a  drum  in  the  machine.  The  machine, 

270 


AN    ELECTRIC   COAL-CUTTER 

Two  miners  working  an  electric  coal-cutter  in  a  mine,  reproduced  from  a  photograph  taken  in  a 
coal  mine.  The  men's  faces  are  seen  peering  out  at  the  two  ends  of  the  machine.  These 
men  have  to  creep  along  a  narrow  passage  which  only  measures  eighteen  inches  from  floor 
to  roof,  and  they  work  hard  in  this  confined  space  right  through  the  night.  In  the  lower 
illustration,  by  permission  of  Mavor  and  Coulson,  Glasgow,  the  coal-cutter  itself  is  shown. 


A   POWERFUL  MACHINE 

which  is  about  eight  feet  long,  is  followed  by  another 
miner,  who  is  controlling  the  working  of  it.  From 
one  side  of  the  machine  extends  a  long  arm  or  drill 
fitted  with  small  points  or  "picks,"  and  this  arm  or 
bar  has  both  a  rotary  motion  and  a  to-and-fro  or  saw- 
like  motion  at  the  same  time.  The  bar  or  cutter  is  put 
into  any  desired  position,  and  may  be  arranged  to  cut 
away  the  fireclay  below  the  coal  seam,  or  if,  instead  of 
fireclay,  there  is  very  hard  rock  or  "pavement"  beneath 
the  coal,  the  cutter  bar  can  be  adjusted  to  cut  along  the  top 
of  the  seam.  This  particular  seam,  which  the  visitor  is 
watching,  is  being  undercut,  and  what  the  machine  really 
does  is  to  cut  away  the  foundation  from  the  coal,  the  bar 
going  in  three  and  a  half  feet  or  even  further. 

The  coal-cutter  travels  along  the  existing  face  of  the 
coal  seam,  cutting  away  the  foundation  and  leaving  a  space 
of  less  than  five  inches  in  height  for  three  and  a  half  feet  in 
under  the  seam,  and  in  one  night  this  machine,  requiring 
only  the  attention  of  two  men,  will  cut  from  one  hundred 
to  one  hundred  and  fifty  yards  in  length.  Of  course  the 
rate  of  progress  is  very  dependent  upon  the  space  in 
which  the  miners  have  to  manipulate  the  machine,  for  as 
new  picks  have  to  be  put  in  several  times  during  the 
night,  this  operation  will  take  much  longer  if  the  miner 
has  to  do  it  while  lying  on  his  face,  side,  or  back.  In 
a  deeper  seam  the  miner  can  use  his  tools  more  easily, 
and  the  largest  cut  of  which  I  have  any  direct  evidence 
is  one  in  a  three-feet  seam,  where  a  length  of  two  hun- 
dred yards  was  undercut  to  a  width  of  five  and  a  half 
feet  in  ten  hours'  time,  for  six  hours  only  of  which  the 
machine  was  actually  working,  which  means  a  speed  of 

271 


A  POWERFUL  MACHINE 

more  than  a  foot  and  a  half  per  minute.  The  nature 
of  the  soil  underlying  the  coal  also  determines  the  speed 
of  the  machine  and  consequently  the  distance  cut  per 
night. 

When  the  coal-cutting  machine  has  cut  away  the 
foundation  from  the  coal  it  has  done  the  hardest  part  of 
the  work.  One  can  imagine  a  miner  having  to  cut  away 
the  foundation  of  an  eighteen-inch  seam  by  hand  while 
lying  down  ;  he  would  probably  do  five  yards  by  the  time 
the  machine  had  done  one  hundred  and  fifty  yards,  but  it 
would  never  pay  him  nor  his  master,  so  that  narrow  seams 
were  formerly  left  in  the  earth.  They  are  now  being 
worked  out  by  these  electric  coal-cutters. 

The  seam  having  been  undercut  by  the  machine  it  only 
remains  to  bring  the  coal  down.  It  may  be  that  gravity 
has  already  brought  it  down  during  the  night,  but  if  not 
the  "  fireman  "  will  in  the  morning  drill  a  few  holes  in  the 
seam  and  blast  it  down,  so  that  it  only  remains  for  the 
collier  to  clear  away  the  coals,  fill  his  hutches,  and  leave 
the  seam  clear  at  the  end  of  the  day  for  the  machine  to 
work  in  during  the  night.  As  already  explained,  the 
cavity  between  the  roads  is  filled  up  each  day  with  stone 
rubbish — that  is  to  say,  the  whole  space  formerly  occupied 
by  the  slice  of  coal  that  has  been  removed  is  now  filled  in 
with  rubbish,  leaving  only  the  continuation  of  these  branch 
roads  through  it.  When  the  slice  is  cut  away  the  stone 
rubbish  is  not,  of  course,  built  in  close  up  to  the  seam,  for 
sufficient  room  must  be  left  to  let  the  electric  coal-cutter 
work  right  along  the  face.  If  the  visitor  now  creeps 
along  the  face  of  the  coal  seam  he  finds  himself  in  a 
passage  about  four  feet  wide,  but  only  eighteen  inches 

272 


LABOUR-SAVING  MACHINERY 

from  floor  to  roof,  and  as  he  goes  along  he  passes  the  ends 
of  these  branch  roads,  any  of  which  will  lead  him  down  to 
the  main  road. 

While  I  say  that  the  electric  coal-cutter  has  done  the 
hard  work,  I  do  not  mean  to  belittle  the  remaining  work 
of  the  collier,  for  it  is  no  light  task  to  work  in  a  narrow 
underground  tunnel  all  day.  Again,  one  has  to  remember 
that  whereas  the  collier  formerly  sent  up  about  two  tons 
of  coal  per  day,  he  has  now  to  send  up  four  or  five  tons  of 
the  coal  cut  by  these  electrical  machines.  He  cannot 
expect  to  be  paid  the  same  price  per  ton  as  formerly,  as 
his  master  has  expended  money  in  cutting  the  coal  for 
him  by  the  electrical  machines,  but  his  wage  remains  as 
good  as  before. 

Some  people  will  picture  the  paying  off  of  a  large 
number  of  miners  whenever  these  labour-saving  appliances 
are  introduced  into  a  mine,  but  on  putting  this  question 
to  the  manager  of  the  Holytown  Collieries  (Scotland)  I 
learned  that  this  was  not  the  case.  The  output  of  the 
pits  is  greatly  increased,  and  a  fourth  pit  has  been  opened 
at  this  particular  colliery,  affording  full  employment  for 
all  their  hands. 

Some  idea  is  given  of  the  work  underground  by  the 
accompanying  photograph.  It  is  curious  to  watch  two 
men  entering  what  is  little  more  than  a  "crack"  in  the 
earth,  and  taking  with  them  a  powerful  machine,  which  is 
receiving  power  from  the  surface  by  means  of  an  electric 
cable. 

The  taking  of  this  photograph  was  by  no  means  an 
easy  task,  not  only  because  of  the  very  confined  space  in 
which  to  produce  sufficient  light,  but  also  owing  to  the 
i  273 


OLD  MINES  REOPENED 

intensely  black  surroundings.  I  am  indebted  to  Mr. 
Diessner,  of  Glasgow,  for  his  kind  assistance  in  securing 
what  at  first  seemed  an  impossible  picture,  and  also  to 
Mr.  Stewart,  of  Pollokshaws,  for  aiding  me  in  making 
preliminary  experiments. 

In  view  of  the  report  of  the  Royal  Commission  on 
Coal  (1905),  it  is  interesting  to  note  that  old  mines  are 
now  being  reopened,  and  narrow  seams  that  formerly 
could  not  be  worked  are  now  being  cut,  at  a  profit,  by 
electrical  machinery. 


274 


CHAPTER  XXVII 

ELECTRICITY  AS   A  HEATING 
AGENT 


What  Sir  Humphry  Davy  discovered—  Arrival  of  the  electric 

—  The  greatest  temperature  produced  on  the  earth—  The  industrial 
electric  furnace—  Electric  welding,  etc.  —Electric  heating  in  the 
home—  A  new  industry. 

WHEN  Sir  Humphry  Davy  produced  an  electric 
arch  or  "arc"  between  two  carbon  points,  he 
was  greatly  impressed  with  the  immense  heat 
produced,  and  he  wrote,  "platinum  is  melted  as  readily  as 
wax  in  the  flame  of  a  candle.1'     The  temperature  of  the 
arc  itself,  that  is,  say,  of  the  bridge  of  carbon  vapour 
between  the  carbon  points,  is  somewhere  about  3,000* 
Centigrade,  or  5,432°  on  Fahrenheit's  scale. 

The  idea  of  constructing  an  electric  furnace  was  a 
natural  result  of  Davy's  discovery.  An  electric  furnace  is 
simply  an  electric  arc  with  suitable  means  for  enclosing  the 
heat  and  preventing  its  escape.  It  has  been  found 
possible,  by  using  special  means  for  conserving  the  heat, 
such  as  lining  the  furnace  with  blocks  of  pure  carbon  and 
encasing  it  in  some  very  refractory  substance,  to  bring  the 
temperature  up  to  4,000°  Centigrade,  which  is  7,232° 
Fahrenheit.  In  the  industrial  electric  furnace  it  is  quite 

275 


THE  ELECTRIC  FURNACE 

easy  to  obtain  temperatures  from  2,000  to  3,500°  Centi- 
grade, or  3,632°  to  6,332°  Fahrenheit. 

To  assist  in  realising  what  an  intense  heat  this  means, 
it  may  be  stated  that  cast-iron  melts  at  1,100°  Centi- 
grade, or  2,012°  Fahrenheit,  and  from  particulars  already 
given  it  will  be  seen  that  it  is  possible  in  the  electric 
furnace  to  reach  a  temperature  nearly  four  times  as 
great. 

Some  electric  furnaces  may  be  arranged  to  deflect  the 
heat  to  any  particular  point,  as  is  done  in  an  ordinary 
blow-pipe.  This  result  is  obtained  by  using  an  electro- 
magnet to  act  upon  the  arc,  which  behaves  exactly  as  a 
conductor  carrying  an  electric  current,  and  thus  having 
a  magnetic  field  it  can  be  repelled  by  a  magnet  of  similar 
polarity. 

There  are  many  devices  for  regulating  the  arc, 
but  the  general  principle  of  the  furnace  is  understood 
from  the  ordinary  electric  arc-lamp,  and  the  simpler  an 
electric  furnace  is  the  better  in  practice,  as  all  its  parts 
are  subjected  to  an  intense  heat. 

There  is  another  class  of  electric  furnace  on  the  same 
principle  as  that  employed  in  the  ordinary  electric  glow- 
lamp,  in  which  lamp  a  carbon  filament  is  heated  by  the 
current.  In  this  furnace  a  current  is  passed  through  a 
resisting  core,  which,  being  usually  composed  of  carbon, 
either  granular  or  in  rods,  offers  a  very  great  resistance 
to  the  current  and  is  raised  to  an  intense  heat.  Such 
furnaces  are  termed  "resistance  furnaces,1'  and  in  some 
of  these  the  material  to  be  heated  or  melted  is  used  as 
part  of  the  conducting  core. 

276' 


ELECTRIC  WELDING 

The  expense  of  obtaining  a  great  heat  from  electricity 
is  very  considerable,  for  only  a  very  small  proportion  of 
the  energy  used  in  generating  the  current  appears  as  heat. 
It  is  obvious  that  under  present  conditions  the  electric 
furnace  will  not  replace  the  much  more  economical  blast 
furnace,  etc.,  but  under  circumstances  where  a  fuel  is  not 
easily  obtainable  and  where  water  power  is  abundant 
the  electric  furnace  is  a  very  convenient  means  of  con- 
verting the  energy  of  the  waterfall  into  heat.  The 
chief  use  of  the  electric  furnace  is  to  obtain  very 
high  temperatures  beyond  any  other  known  means  in 
practice. 

There  is  a  third  kind  of  electric  furnace  which  will  be 
better  understood  from  the  chapter  on  "Electricity  and 
Chemistry,'1'  as  it  is  the  chemical  action  of  the  current  upon 
the  materials  that  is  made  use  of,  while  the  substance 
is  kept  in  a  heated  condition.  These  are  known  as 
electrolytic  furnaces,  and  it  is  this  class  of  furnace  that 
has  made  aluminium  a  marketable  metal. 

Where  an  intense  heat  is  required  at  any  particular 
point,  such  as  in  welding  boiler  plates,  etc.,  the  electric 
arc  is  very  convenient,  as  it  may  be  taken  to  any  part 
of  the  boiler,  one  of  the  wires  from  the  dynamo  being 
fastened  to  the  boiler  plate,  while  the  other  is  fixed  to 
a  portable  insulating  holder.  As  soon  as  the  carbon  is 
made  to  touch  the  plate  and  is  then  withdrawn  about  a 
quarter  of  an  inch,  an  arc  is  formed  and  an  intense  heat 
produced. 

There  are  many  different  uses  to  which  electric  heating 
may  be  put,  and  among  the  latest  is  a  small  furnace 

277 


ELECTRIC  HEATING   IN  THE   HOME 

by  which  dentists  may  fuse  a  very  refractory  substance  as 
a  filling  in  teeth.  The  dentist  may  also  use  electricity 
for  heating  air  to  be  blown  upon  a  tooth  for  drying 
purposes,  thus  obtaining  a  stream  of  air  at  constant 
temperature. 

It  is  quite  possible  to  cook  food  by  means  of  electricity, 
but  it  is  at  present  an  expensive  luxury.  It  is  very  con- 
venient to  be  able  to  switch  on  the  current  to  a  kettle  on 
the  breakfast-table  and  reboil  the  water  for  those  foolish 
young  friends  who  think  life  is  so  long  that  they  can 
afford  to  spend  nearly  the  half  of  their  time  upon  earth 
in  their  beds. 

It  is  very  nice,  especially  in  summer  time,  to  let  the 
laundry-maid  do  her  ironing  without  requiring  a  roasting 
fire  by  simply  heating  some  highly  resisting  wires  in  the 
heating-iron  by  passing  a  current  of  electricity  through 
them.  The  cook  finds  it  an  advantage  to  switch  on  the 
heat  to  her  range  without  bothering  about  the  laying 
of  a  fire.  The  whole  house  may  be  very  comfortably 
warmed  by  electricity,  and  even  bed-quilts  heated  by 
fine  wires  inside  have  been  made,  whether  with  or 
without  the  knowledge  of  the  Fire  Insurance  Com- 
panies I  cannot  say,  but  these  are  certainly  luxuries  for 
those  who,  fortunately  or  otherwise,  do  not  require  to  keep 
an  eye  on  the  amount  of  their  household  expenditure. 

In  connection  with  the  electric  furnace,  it  may  be 
mentioned  that  within  the  last  few  years  there  has  sprung 
up  a  new  industry  in  the  manufacture  of  "peat-coal." 
The  peat  is  carbonised  in  an  electric-resistance  furnace, 
and  may  be  produced  at  about  five  shillings  per  ton. 

278 


A   NEW   INDUSTRY 

Among  other  uses  of  the  electric  furnace  the  most 
prominent  are  the  manufacture  of  glass  and  phosphorus, 
and  the  production  of  carbide  of  calcium  which  is  required 
for  the  making  of  acetylene  gas. 


279 


CHAPTER  XXVIII 
ELECTRICITY'S  RELATION  TO  HEAT 

Our  fickle  sense  of  heat — Early  ideas  about  heat— Different  origins  of 
heat— Heat  produces  electricity  and  electricity  produces  heat— A 
thermometer  so  sensitive  that  it  will  measure  to  the  one-millionth 
part  of  a  degree — How  it  is  possible  to  measure  temperatures  up 
to  thousands  of  degrees— A  tell-tale  instrument  that  reports  any 
carelessness  in  furnace  stoking,  etc.— A  simple  experiment  shows 
a  very  close  connection  between  heat  and  electricity— What  our 
great-grandchildren  will  think  of  our  "  up-to-date  "  methods— The 
increasing  need  of  specialists— Some  remarks  about  ether  waves. 

OUR  sensations  of  heat  are  merely  comparative. 
It  is  amusing  sometimes,  on  going  out  of  doors 
in  the  morning,  to  note  the  different  opinions  as 
to  the  prevailing  temperature.  One  is  sometimes  greeted 
with  the  remark  that  it  is  a  cold  morning,  while  within 
a  short  distance  someone  else  remarks  that  it  is  a  mild 
morning.  People  compare  the  temperature  with  the  con- 
dition of  their  own  bodies,  and  if  one  person  steps  out 
of  the  cold  air  into  a  warm  room  he  may  say  the  latter 
is  much  overheated,  while  the  occupant  finds  it  just 
comfortable.  This  is  very  forcibly  demonstrated  by  the 
simple  experiment  of  taking  three  basins  of  water,  having 
the  centre  one  filled  with  tepid  water,  and  one  of  the 
others  with  very  hot  water,  while  the  third  has  very 

280 


EARLY  IDEAS  ABOUT   HEAT 

cold  water.  Keeping  the  one  hand  in  the  hot  water  and 
the  other  hand  in  the  cold  water  till  they  become  accus- 
tomed to  the  respective  temperatures,  and  then  plunging 
both  hands  into  the  tepid  water,  the  hand  from  the  hot 
water  complains  of  the  coldness  of  the  tepid  water,  while 
the  hand  from  the  cold  basin  feels  the  same  water  warm. 

A  youngster  would  consider  his  bath  quite  warm 
enough,  and  possibly  too  warm,  at  100°  Fahrenheit,  while 
a  complaint  would  be  made  that  his  porridge  or  tea  at 
the  same  temperature  was  too  cold.  It  is  clear,  therefore, 
that  we  cannot  depend  upon  our  own  sensations ;  we  must 
pay  attention  to  the  effects  and  origin  of  heat  in  other 
things. 

Electricity  has  proved  a  most  useful  assistant  in  the 
investigation  of  high  temperatures,  as  will  be  shown  at 
the  close  of  this  chapter,  but  this  is  not  the  main  relation- 
ship indicated  in  the  title  used  for  the  present  chapter. 

The  early  scientists  believed  heat  to  be  some  subtle 
material  substance  which  could  be  expelled  from  one 
body  and  taken  up  by  another,  but  we  now  know  that 
heat,  as  reaching  us  from  the  sun,  is  merely  an  ether 
disturbance,  which,  falling  upon  the  material  things  of 
this  globe,  including  our  atmosphere,  sets  the  molecules 
into  rapid  vibratory  motion,  and  that  this  vibratory 
movement  may  be  increased  to  a  point  at  which  the 
molecules  can  no  longer  hold  together,  so  that  a  solid,  by 
the  application  of  heat,  becomes  a  liquid,  and  in  turn 
a  liquid  becomes  gaseous.  We  also  use  the  word  heat 
to  signify  this  molecular  vibration  in  a  body.  Travelling 
in  an  opposite  direction,  we  find  that  a  compound  gas, 
such  as  air,  or  a  simple  gas,  such  as  hydrogen  or  oxygen, 

281 


HEAT  PRODUCES   ELECTRICITY 

will,  when  the  vibratory  motion  called  heat  is  reduced, 
become  liquid,  and  when  a  sufficiently  low  temperature 
is  produced  liquid  air  may  even  become  frozen  or  solid; 
and  if  it  were  possible  to  reach  a  point  of  absolute 
zero,  at  which  there  would  be  no  vibratory  motion, 
the  molecules  would  doubtless  fall  to  pieces.  Follow- 
ing this  line  of  thought,  one  is  tempted  to  wonder 
whether  if  it  were  possible  to  rob  the  atoms  of  all 
internal  motion  they  would  not  cease  to  be  matter  and 
become  part  of  the  great  ether  ocean. 

We  have  a  mechanical  origin  of  heat,  as  is  forcibly 
exhibited  when  a  steam-hammer,  by  repeated  blows,  raises 
a  piece  of  iron  to  a  red  heat.  There  is  also  a  chemical 
origin  of  heat,  as  daily  demonstrated  in  our  fireplaces  by 
the  chemical  changes  we  call  combustion.  But  what 
concerns  us  most  in  this  chapter  is  that  there  is  an 
electrical  origin  of  heat,  as  is  exhibited  in  an  electric 
lamp,  or,  indeed,  in  any  conductor  carrying  an  electric 
current.  In  addition  to  these  there  is  a  radiative  origin, 
as  already  indicated  by  reference  to  the  sun  sending  out 
ether  waves  which  produce  molecular  movement  in 
matter. 

We  have  seen  in  a  former  chapter  that  while  electricity 
may  produce  magnetism,  the  converse  is  also  true,  for 
magnetism  produces  electricity.  In  the  dynamo  we  found 
mechanical  motion  producing  electricity,  while  in  the 
motor  we  saw  electricity  transformed  to  mechanical 
motion.  In  a  similar  way,  while  electricity  produces 
heat,  it  is  likewise  true  that  heat  produces  electricity. 

In  the  twenties  of  last  century  Professor  Seebeck,  of 
Berlin,  was  experimenting  with  simple  couples  of  metals, 

282 


THERMO-ELECTRICITY 

and  thereby  studying  the  Volta  contact  theory  referred 
to  in  chapter  iii.5  when  he  observed  that  if  the  point 
of  contact  of  any  two  metals  was  heated  a  constant 
current  of  electricity  was  set  up  in  the  connecting  wire. 
This  was  easily  demonstrated  by  placing  a  pivoted  mag- 
netic needle,  to  act  as  a  detector  of  current,  upon  a  block 
of  the  metal  bismuth  and  forming  an  arch  of  copper 
over  the  needle,  the  copper  being  joined  to  the  bismuth 
at  the  two  ends  of  the  block.  When  a  lamp  was  placed 
at  one  of  the  junctions  of  the  metals,  the  magnetic 
needle  turned  outwards,  indicating  a  current  of  electricity 
flowing  in  the  neighbouring  metals,  just  as  the  needle 
telegraph  replies  to  the  current  in  its  surrounding  coil. 
In  this  way  it  was  found  that  if  any  two  dissimilar  metals 
were  joined  together  and  the  junction  heated,  there 
would  be  a  flow  of  electricity  in  a  wire  joining  the  two 
extremities  of  the  metals  together,  provided  these  were 
kept  at  a  lower  temperature  than  the  junction. 

Electricity  produced  by  such  means  is  termed  thermo- 
electricity, the  name  merely  indicating  its  source.  People 
set  about  making  batteries  or  "piles"  of  these  couples, 
but  the  electro-motive  force  of  such  a  thermo-couple  was 
found  to  be  very  small  when  compared  with  that  of  an 
ordinary  voltaic  cell.  Bismuth  and  antimony  are  the 
metals  usually  employed  for  experimental  thermo-couples, 
but  these  are  of  chief  interest  to  the  scientist. 

One  practical  adaptation  of  the  thermo-couple  is  in 
obtaining  very  exact  measurements  of  differences  of  tem- 
perature, one  invention  being  capable  of  detecting  a 
difference  of  less  than  one-millionth  part  of  a  degree.  Of 
course,  an  instrument  of  such  delicacy  is  not  required  in 

283 


A  TELL-TALE  INSTRUMENT 

everyday  life,  but  it  is  useful  in  a  scientific  laboratory. 
It  is  very  important,  however,  in  the  industrial  world  that 
we  should  have  means  of  reading  very  high  temperatures, 
such  as  the  heat  of  a  blast  furnace  or  a  pottery  kiln,  and 
for  such  purposes  a  thermo-couple  comes  in  as  a  very 
useful  servant. 

If  a  thermo-couple,  protected  in  a  fireproof  porcelain 
tube,  be  inserted  in  the  source  of  heat,  the  temperature  of 
which  is  desired  to  be  known,  there  will  be  a  current  of 
electricity  passing  out  along  the  connecting  wires,  and 
this  current  will  be  in  proportion  to  the  amount  of  heat 
producing  it,  so  all  we  now  require  is  a  delicate  galvano- 
meter, which  is  a  magnet  capable  of  turning  in  a  sur- 
rounding coil  of  wire,  to  indicate  the  presence  and  the 
amount  of  the  current.  The  more  current  that  passes, 
the  farther  will  the  magnet  be  turned  round,  so  that  a 
scale  may  be  marked  off  representing  heat  degrees,  and  so 
arranged  that  the  magnet  will  point  out  the  temperature 
corresponding  to  the  current  set  up  by  that  particular 
degree  of  heat.  Such  instruments  are  generally  called 
pyrometers,  and  are  capable  of  reading  temperatures  as 
high  as  3,000°  Fahrenheit.  They  may  be  made  to 
read  any  temperature,  provided  the  thermo-couple  is 
able  to  withstand  the  heat. 

Pyrometers  may  be  made  to  record  the  variations  of 
these  high  temperatures,  and  one  can  imagine  these  little 
tell-tale  recorders  locked  up  all  night  in  the  darkness  of 
the  manager's  private  office,  but  truthfully  informing  him 
in  the  morning  of  any  carelessness  or  irregularity  on  the 
part  of  those  whose  duty  it  is  to  keep  the  furnaces,  etc., 
at  a  constant  temperature. 

284 


OUR  "UP-TO-DATE"  METHODS 

The  electro-magnetic  effect  of  the  coil  upon  the  magnet 
is  so  very  small  that  much  skill  is  required  in  the  making 
of  these  instruments,  and  I  have  seen  a  difficulty  arise 
from  such  a  small  cause  as  a  trace  of  iron  being  in  the 
brass  of  a  very  small  screw,  which  being  carried  by  the 
indicator  affected  its  behaviour  towards  the  thermo- 
current.  A  well-made  pyrometer  is  quite  reliable,  and 
this  is  a  use  of  thermo-electricity  which,  no  doubt,  will  be 
valued  more  as  our  industries  advance  along  more  scien- 
tific lines. 

Although  thermo-batteries  have  been  used  in  France 
for  working  telegraphs  and  even  for  lighting  glow-lamps 
on  a  small  scale,  their  present  use  is  as  a  sensitive 
measurer  of  very  slight  differences  of  temperature,  and  as 
an  indicator  of  extreme  heat  or  cold. 

It  would  be  folly  to  think  that  scientists  have  already 
got  to  the  "end  of  things"  as  regards  the  most  econo- 
mical method  of  obtaining  electric  currents.  Ultimately 
man  may  find  a  means  of  dispensing  with  the  clumsy 
method  of  converting  heat  into  mechanical  energy  by 
means  of  the  steam-engine,  which  is  done  at  an  enormous 
loss,  for  it  is  a  remarkable  fact  that  the  very  best  steam- 
engines  of  our  times  can  only  give  us  about  twelve  per 
cent,  of  the  energy  in  coal.  Our  great-grandchildren 
will  doubtless  consider  our  "up-to-date*"  methods  very 
crude,  for  with  the  steady  advance  of  scientific  knowledge, 
there  is  bound  to  be  an  equivalent  advance  in  the  indus- 
trial world. 

The  short  time  we  are  upon  this  earth  does  not  give  us 
opportunity  to  explore  thoroughly  more  than  a  few  of  the 
main  paths  of  knowledge,  or  possibly  only  a  single  main 

285 


REMARKS   ABOUT   ETHER  WAVES 

road  and  some  of  its  side  lanes  or  ramifications,  so  that 
as  the  accumulation  of  knowledge  goes  on  at  a  quickly 
increasing  rate,  the  need  of  specialists  will  become  even 
much  more  marked  than  is  the  case  at  present. 

In  closing  this  chapter,  it  may  be  remarked  that 
although  heat  waves  in  the  ether  were,  until  quite 
recently,  believed  to  be  entirely  different  in  character 
from  light  waves  and  actinic  or  chemical  waves,  the  dis- 
tinction is  fast  disappearing,  and  the  tendency  is  to 
consider  all  these  ether  waves  as  "  light "  waves  whether 
affecting  the  vision  or  not,  and  it  is  in  this  connection 
that  a  new  word  is  required  to  save  confusion  with  the 
word  "light"  as  used  to  denote  a  sensation.  It  is  now 
becoming  more  common  to  speak  of  heat  as  the  pheno- 
menon exhibited  in  matter,  and  to  call  the  heat  waves  in 
the  ether  "  radiant  energy." 

All  ether  waves  are  set  up  by  the  vibratory  movement 
of  molecules  and  atoms  of  matter.  As  already  indicated, 
the  molecular  energy  in  the  sun  disturbs  the  all-pervading 
ether,  which  again  sets  up  molecular  motion  in  matter, 
and  so  on. 

The  connecting  link  between  matter  and  the  ether  will 
be  explained  when  we  come  to  consider  what  we  know 
about  electricity. 


286 


CHAPTER  XXIX 

HOW   ELECTRICITY  AIDS  THE 
CONJURER 

A  spirit  se*ance— A  most  remarkable  borrowed  penny— How  the  audi- 
ence are  led  astray— A  wizard  of  sixty  years  ago— An  extraordinary 
mansion. 

ELECTRICITY  is  a  very  helpful  assistant  in  en- 
abling the  conjurer  to  delude  his  audience.  There 
is  no  mystery  now  in  a  drum  beating  while  sus- 
pended in  the  air,  or  in  musical  instruments  playing  in 
inaccessible  parts  of  a  hall,  as  the  public  have  become  well 
versed  in  the  electrical  transmission  of  power ;  but  a  very 
good  representation  of  a  "  spirit-rapping  seance "  may  be 
given  by  similar  means.  It  is  not  my  intention  to  attempt 
to  expose  the  methods  of  any  public  entertainer,  but  on 
several  occasions  I  have  concocted  and  performed  some 
electrical  "  magic  "  for  amusement  at  entertainments  given 
in  behalf  of  charities,  and  I  shall  use  some  of  these  as 
illustrations  of  how  electricity  aids  the  conjurer. 

In  order  to  give  an  imitation  of  a  spirit  seance  one  may 
place  an  empty  tin  box  upon  a  little  table  at  the  front  of 
the  stage,  and  then,  calling  on  the  ethereal  spirit  to 
come  and  make  itself  manifest,  make  the  audience  hear, 
above  the  soft  musical  refrain  from  the  piano,  a  distinct 
series  of  raps,  first  of  all  in  some  inaccessible  corner,  and 

287 


A   SPIRIT  STANCE 

then  coming  gradually  nearer  the  stage  till  the  rapping  is 
distinctly  heard  upon  the  table,  and  ultimately  upon  the 
empty  tin  box,  which  has  been  previously  examined  by 
one  or  more  members  of  the  audience  and  placed  by  one 
of  them  upon  the  table. 

If  one  of  the  audience  now  selects  any  card  from  a  pack 
of  playing-cards,  the  spirit  will  tell  the  number  of  the 
card,  and  when  asked  to  answer  by  a  single  rap  whether 
the  card  belongs  to  hearts,  clubs,  diamonds,  or  spades,  it 
will  remain  silent  till  the  right  suit  is  named,  and  the 
conjurer  is  able  to  assure  the  audience  that  he  did  not 
know  what  card  had  been  selected  until  he  heard  the  raps 
from  the  empty  box.  A  good  deal  of  amusement  can  be 
obtained  from  such  imitations,  and  there  can  be  little 
secret  here  to  disclose,  for  it  is  evident  that  the  raps  are 
produced  by  hidden  electro-magnetic  devices  similar  in 
principle  to  an  ordinary  single-stroke  bell.  The  raps  on 
the  empty  tin  box  are  really  taking  place  on  a  long  flat 
tin  box  concealed  under  the  table-top;  and  all  these 
devices,  placed  in  different  parts  of  the  room,  are  under 
the  control  of  an  assistant  behind  the  scenes. 

The  rest  is  mere  trickery,  as,  for  instance,  with  the 
cards.  The  conjurer  has  one  complete  pack  of  playing- 
cards,  and  in  addition  many  packs  of  the  same  appear- 
ance, but  each  of  these  consisting  of  fifty-two  cards  of  one 
particular  value,  the  ace  of  spades,  the  ten  of  diamonds, 
and  so  on.  The  conjurer,  of  course,  merely  exhibits  the 
complete  and  honest  pack,  and  while  he  is  asking  a 
member  of  the  audience  to  select  any  card,  he  exchanges 
the  pack  for  one  of  the  faked  ones.  In  order  that  he  may 
say  to  the  audience  that  he  does  not  know  the  selected 

288 


REMARKABLE  BORROWED  PENNY 

card,  he  simply  picks  up  at  random  any  one  of  the  faked 
packs  before  going  on  the  stage,  and,  without  looking  at 
it  himself,  he  hands  the  hidden  confederate  one  of  the 
cards,  so  that  this  assistant  controlling  the  electric 
switches  will  now  be  able  to  cause  the  tin  box  to  rap  out 
the  number  and  suit  of  the  card  which  will  necessarily  be 
selected  by  the  audience.  This  seance  may,  of  course,  be 
extended  in  a  great  variety  of  ways. 

To  take  as  another  illustration  a  trick  which  I  recently 
invented,  and  which  met  with  the  approval  of  a  large 
audience.  Coming  upon  the  stage  I  place  two  small  tables 
in  the  front,  one  at  either  end  of  the  platform.  I  then 
request  the  temporary  loan  of  one  penny,  which  is  easily 
obtained,  but  so  that  there  may  be  no  misunderstanding  I 
ask  the  lender  if  he  will  be  good  enough  to  mark  the 
penny  with  his  knife  in  any  way  he  desires  so  that  he  will 
not  fail  to  recognise  it  again.  This  having  been  done 
behind  my  back,  I  request  a  lady,  close  at  hand,  to  seal 
the  penny  up  in  an  envelope  and  retain  it  meantime. 
Going  upon  the  stage  I  exhibit  an  empty  tin  box,  and 
assuring  the  audience  that  it  is  empty  and  contains  no 
hidden  machinery  of  any  kind,  I  request  that  anyone 
desiring  to  examine  the  box  for  himself  should  do  so. 
A  gentleman  comes  forward,  but  as  soon  as  the  box  is 
touched  it  deals  out  a  series  of  sudden  shocks,  so  that 
the  examiner  refuses  to  have  anything  more  to  do  with  it, 
and  no  one  else  seems  willing  to  risk  electrocution,  while 
the  convulsive  jumps  of  the  would-be  inspector  have 
given  the  audience  and  himself  some  amusement.  Remark- 
ing to  the  audience  that  I  suffer  no  inconvenience  in  the 
handling  of  the  box,  I  proceed  to  close  it,  not  only 

T  289 


REMARKABLE  BORROWED  PENNY 

putting  its  lid  on,  but  also  tying  a  ribbon  around  it  to 
ensure  the  lid  remaining  firmly  closed.  Holding  the  box 
by  the  ribbon  I  place  it  upon  four  glass  tumblers,  which 
act  as  transparent  legs  to  keep  the  box  clear  of  the  table, 
and  insulated  from  the  rest  of  the  material  world.  Now 
taking  a  pasteboard  box  down  to  the  audience  I  request 
the  lady,  who  has  meantime  held  the  borrowed  penny,  to 
place  it  and  its  enclosing  envelope  inside  this  box,  she 
tying  a  ribbon  around  it  to  prevent  my  opening  it, 
Carrying  this  box  by  the  ribbon,  and  keeping  it  in  view 
of  the  audience  all  the  time,  I  place  it  upon  four  other 
glass  tumblers  on  the  little  table  at  the  opposite  end  of 
the  stage  from  the  tin  box.  Then  standing  right  in  the 
centre  of  the  stage,  I  tell  the  audience  that  the  borrowed 
penny  is  now  in  the  pasteboard  box,  securely  sealed  up  in 
the  envelope,  just  exactly  as  the  lady  placed  it  there. 
It  may  be  remarked  here  that  some  people  think  that  a 
conjurer  has  a  special  licence  to  say  a  thing  is  somewhere 
when  it  is  not,  but  that  is  never  the  case.  He  may  pre- 
tend to  place  something  where  he  really  does  not,  but 
when  he  tells  the  audience  that  the  borrowed  article  is  in 
a  certain  place,  then  it  really  is  there.  Thus  assuring  the 
audience  that  the  borrowed  penny  is  still  in  the  paste- 
board box,  I  ask  them  to  pay  particular  attention  to  my 
movements,  watching  that  I  never  go  near  either  of  the 
tables.  I  then  command  that  the  penny  should  break  up 
into  its  individual  molecules,  so  that  it  may  easily  pass 
out  through  its  imprisonment.  A  little  gentle  music  from 
the  pianist  and  I  inform  the  audience  that  if  they  can  see 
a  sort  of  mist  hanging  over  the  stage  they  can  then  see  the 
penny  in  solution. 

290 


REMARKABLE  BORROWED  PENNY 

I  then  command  that  the  penny  shall,  after  a  few  bars 
of  lively  music,  quickly  rush  together  again  and  fall  down 
inside  one  of  the  four  tumblers  under  the  tin  box  on  the 
other  table.  At  the  moment  when  the  music  ceases  the 
penny  is  distinctly  heard  to  fall  into  one  of  the  tumblers, 
but  not  satisfied  with  this,  and  still  standing  in  the  centre 
of  the  stage,  I  ask  the  penny  to  once  more  quickly  disinte- 
grate and  pass  through  into  the  tin  box.  A  few  bars  of 
music  and  the  audience,  listening  to  the  movement  of  the 
penny,  are  satisfied  that  it  has  entered  the  box,  but  to 
show  how  well  under  control  it  is,  I  ask  the  penny  to  spin 
round  on  the  bottom  of  the  box.  This  done,  and  still 
remaining  in  the  centre  of  the  stage,  I  request  the  gentle- 
man who  was  good  enough  to  lend  me  the  penny  to  come 
up  on  the  stage  himself  and  open  the  tin  box,  and  I  ask 
him  to  tell  the  audience  quite  frankly  whether  or  not  it  is 
his  penny  that  is  now  in  the  tin  box,  and  I  assure  the 
gentleman  that  if  he  finds  the  marks  as  he  made  them  he 
may  be  certain  that  there  is  no  trickery  there,  as  I  have 
not  the  faintest  idea  how  he  marked  the  coin,  nor  has  any 
confederate  seen  or  handled  it. 

Having  removed  the  ribbon  and  the  lid,  the  lender 
carefully  examines  the  penny,  which  he  emphatically 
declares  to  be  the  borrowed  penny  and  no  other. 

I  then  ask  the  gentleman  if  he  will  be  good  enough  to 
lift  the  pasteboard  box  off  the  other  table  and  take  it 
down  to  the  lady  who  deposited  the  penny  in  it.  She 
finds  the  envelope  empty,  but  without  any  trace  to 
indicate  how  the  penny  escaped. 

More  than  one  scientific  friend  remarked  to  me  after 
the  performance,  that  if  it  was  really  true  that  the 

291 


AUDIENCE   LED   ASTRAY 

borrowed  penny  was  still  in  the  pasteboard  box  after  I 
left  it  on  the  table,  it  seemed  an  utter  impossibility 
that  the  lender  should  find  it  in  the  tin  box.  I  not  only 
assured  them  that  the  penny  was  left  in  the  pasteboard 
box,  but  it  was  also  true  that  I  never  handled  the  borrowed 
coin  after  handing  it  over  to  the  lady  for  sealing  up  in 
the  envelope. 

All  this,  doubtless,  seems  mysterious,  and  yet  it  is  very 
simple  from  behind  the  scenes,  for  it  is  very  much  easier 
to  make  up  an  entanglement  of  this  kind  than  it  is  for  an 
outsider  to  disentangle  it. 

First  of  all  the  electrical  apparatus  is  very  simple  and 
is  merely  to  deceive  the  sense  of  hearing,  upon  which  the 
audience  are  going  to  depend  as  to  the  whereabouts  of  the 
borrowed  penny.  I  first  of  all  made  up  a  flat  glass  vessel, 
to  be  placed  immediately  under  the  table-top,  and  I  sup- 
ported a  penny  over  this  glass  box  by  drilling  a  hole  in 
the  coin  and  passing  a  fine  silver  wire  through  it  and  over 
the  top  of  the  box.  The  silver  wire  was  connected  to 
wires  leading  down  the  legs  of  the  table  and  thence  under 
the  carpet  to  the  back  of  the  stage,  where  an  assistant 
could  switch  on  an  electric  current  and  fuse  the  fine  silver 
wire,  allowing  the  penny  to  fall  into  the  glass  vessel  at 
the  desired  moment.  This  jingling  noise  of  the  falling 
penny  really  takes  place,  of  course,  in  the  glass  vessel 
immediately  under  the  table-top,  but  the  audience  believe 
it  to  occur  in  the  tumbler.  A  similar  stretched  wire  and 
penny  placed  over  a  hidden  tin  box  completes  the  decep- 
tion as  far  as  the  dropping  of  the  penny  is  concerned. 
Another  tin  box  with  a  simple  electro-magnetic  device 
sets  a  penny  spinning  on  the  bottom  of  a  box.  The 

292 


AUDIENCE   LED  ASTRAY 

audience  hear  these  sounds  while  intently  watching  the 
box  and  tumblers  on  the  top  of  the  table,  and  the  decep- 
tion is  wonderfully  efficient. 

While  the  conjurer  here  depends  upon  electricity  to 
produce  the  desired  effect  as  far  as  the  senses  are  con- 
cerned, there  must  be  an  attempt  to  mystify  the  mind,  or 
to  lead  the  thoughts  of  the  audience  astray.  The  most 
misleading  part  of  the  trick  really  consists  in  my  being 
able  to  deceive  the  audience  as  to  the  identity  of  the 
borrowed  penny. 

To  make  the  matter  quite  clear  let  us  first  of  all 
merely  follow  the  borrowed  penny.  I  took  it  from  the 
gentleman,  handed  it  to  the  lady,  who  sealed  it  in  an 
envelope,  and  later  on  placed  it  in  the  pasteboard  box. 
The  box  was  taken  on  to  the  stage,  the  penny  was  never 
touched,  and  still  lay  there  where  it  was  put  till  the  trick 
was  over  and  done  and  the  audience  away.  I  made  the 
box  with  a  false  bottom  so  arranged  that  it  at  first  acted 
as  one  of  the  sides,  being  folded  back  against  the  real 
side,  and  I  had  previously  placed  an  empty  envelope, 
identical  in  appearance  to  the  one  I  gave  to  the  lady, 
between  the  false  bottom  and  the  side,  so  that  when  the 
lady  deposited  the  envelope  with  the  borrowed  penny  in 
the  box,  the  false  bottom  closed  down  upon  it,  safely 
hiding  it  and  exposing  in  its  place  the  empty  envelope,  to 
be  discovered  there  later  on.  This  was  the  borrowed 
penny,  but  it  was  not  the  penny  the  lender  marked,  for 
when  he  handed  me  the  penny  at  the  outset  I  pretended 
just  to  recollect,  as  I  was  taking  it  from  him,  that  it 
would  be  better  to  mark  it,  whereas  I  really  handed  him 
another  penny  of  my  own  which  I  had  hidden  in  the 

293 


AUDIENCE  LED   ASTRAY 

palm  of  my  hand.  He  took  this  penny  believing  it  to  be 
the  penny  he  had  just  taken  out  of  his  pocket,  and  if 
questioned  I  doubt  if  he  would  admit  that  the  penny  ever 
left  his  hand,  and  so  he  marked  this  penny  of  mine.  I 
retained  this  marked  penny,  leaving  the  borrowed  penny 
with  the  lady,  and  while  the  audience  were  laughing  at 
the  eccentricities  of  the  gentleman  who  got  a  shock  on 
touching  the  tin  box,  I  placed  this  marked  penny  on  the 
bottom  of  the  tin-box,  then  put  the  lid  on  and  tied  it  up. 

The  trick  was,  of  course,  really  over,  as  far  as  I  was 
concerned,  before  it  had  begun  in  the  minds  of  the 
audience,  and  this  is  a  safe  principle  upon  which  to  build 
up  a  trick. 

I  was  able  to  say  truthfully  that  the  borrowed  penny 
was  in  the  pasteboard  box,  and  it  was  the  lender  who 
examined  the  marked  penny  in  the  tin  box  and  said  that 
it  was  his  penny.  It  certainly  was  the  penny  he  marked, 
but  not  the  borrowed  penny,  and  so  the  mystery  was 
obtained, 

In  order  to  deal  out  electric  shocks  from  the  tin  box  to 
the  would-be  inspector  I  had  previously  deposited  two 
large  pieces  of  sheet-iron  below  the  carpet,  and  connected 
these  to  a  battery  and  induction  coil,  under  the  control 
of  an  assistant  behind  the  scenes.  When  I  stood  on  one 
hidden  plate,  and  the  member  of  the  audience  over  the 
other  plate,  we  completed  the  circuit  through  the  box  in 
our  hands.  Of  course  I  received  a  similar  shock  to  the 
victim,  but,  being  prepared  for  it,  I  took  it  more  calmly. 
This  part  of  the  trick  was  merely  a  "  blind  "  to  give  the 
amateur  conjurer  a  safe  opportunity  of  placing  the 
marked  penny  in  the  box  without  attracting  attention. 

294 


WIZARD  OF  SIXTY  YEARS  AGO 

One  would  hardly  credit  how  much  the  audience  really 
see  in  their  imagination.  I  have  heard  the  narration  of 
some  of  my  own  tricks  by  members  of  the  audience,  and 
it  is  really  quite  remarkable  how  the  actual  facts  are 
altered  by  their  imaginative  powers.  This  somewhat 
lengthy  description  will  serve  to  illustrate  the  application 
of  electricity  to  the  "  black  art." 

A  very  interesting  account  was  published,  about  a 
quarter  of  a  century  ago,  of  how  Robert  Houdin,  a 
famous  French  conjurer,  amused  himself  after  his  retire- 
ment to  a  beautiful  mansion  in  the  village  of  St.  Gervais. 
From  this  account  I  have  extracted  those  parts  seeming  of 
most  interest.  In  describing  the  mansion  the  writer, 
presumably  Houdin  himself,  says  with  reference  to  the 
avenue  gateway,  distant  about  a  quarter  of  a  mile  from 
the  house :  "  The  visitor  presenting  himself  before  the 
door  on  the  left  sees  a  gilt  plate  bearing  the  name  of 
Robert  Houdin,  below  which  is  a  small  gilt  knocker.  He 
raises  this  according  to  his  fancy,  but,  no  matter  how 
feeble  the  blow,  a  delicately  tuned  chime  of  bells  sounding 
through  the  mansion  announces  his  presence.  When  the 
attendant  touches  a  button  placed  in  the  hall  the  chime 
ceases,  the  bolt  at  the  entrance  is  thrown  back,  the  name 
of  Robert  Houdin  disappears  from  the  door,  and  in  its 
place  appears  the  word  '  entrez '  in  white  enamel.  The 
visitor  pushes  open  the  door  and  enters,  it  closes  with  a 
spring  behind  him,  and  he  cannot  depart  without  per- 
mission. 

"This  door  in  opening  sounds  two  distinct  chimes, 
which  are  repeated  in  the  inverse  order  in  closing.  Four 
distinct  sounds  then,  separated  by  equal  intervals,  are 

295 


AN  EXTRAORDINARY  MANSION 

produced.  In  this  way  a  single  visitor  is  announced.  If 
many  come  together,  as  each  holds  the  door  open  for  the 
next,  the  intervals  between  the  first  two  and  the  last 
two  strokes  indicate  with  great  accuracy,  especially  to  a 
practised  ear,  the  number  who  have  entered,  and  the 
preparation  for  the  reception  is  made  accordingly.  A 
resident  of  the  place  is  readily  distinguished ;  for,  know- 
ing in  advance  what  is  to  occur,  he  knocks,  and  at  the 
instant  that  the  bolt  slips  back  he  enters.  The  equi- 
distant strokes  follow  immediately  the  pressing  of  the 
button.  But  a  new  visitor,  surprised  at  the  appearance 
of  the  word  'entrez,'  hesitates  a  second  or  two,  then 
presses  open  the  door  gradually,  and  enters  slowly.  The 
four  strokes  now  indicated  by  a  short  interval  succeed 
the  pressing  of  the  button  by  quite  an  appreciable  time ; 
and  the  host  makes  ready  to  receive  a  stranger.  The 
travelling  beggar,  fearful  of  committing  some  indiscretion, 
raises  timidly  the  knocker;  he  hesitates  to  enter,  and 
when  he  does,  it  is  only  with  great  slowness  and  caution. 
This  the  chimes  unerringly  announce.  It  seems  to  persons 
at  the  house  as  if  they  actually  saw  the  poor  mendicant 
pass  the  entrance ;  and  in  going  to  meet  him  they  are 
never  mistaken.1" 

Electrical  arrangements  were  also  provided  for  signalling 
the  arrival  of  a  carriage  and  dealing  with  the  gates  in 
response ;  while  the  postman  received  from  a  bell  at  the 
gate  instructions  whether  to  leave  the  letters  in  the  box, 
or  if  it  was  necessary  for  him  to  go  up  to  the  house  to 
collect  some  letters. 

"My  electric  doorkeeper,"  says  Houdin,  "leaves  me 
nothing  to  be  desired.  His  service  is  most  exact ;  his 

296 


AN  EXTRAORDINARY  MANSION 

fidelity  is  thoroughly  proven ;  his  discretion  is  unequalled; 
and  as  to  his  salary,  I  doubt  the  possibility  of  obtaining 
an  equal  service  for  a  smaller  remuneration."" 

Houdin  had  a  favourite  mare,  to  which  he  was  much 
attached,  and  the  food  for  this  horse  was  automatically 
placed  in  its  trough  thrice  daily,  the  apparatus  being 
controlled  by  a  clock  in  the  study.  The  reason  for  this 
arrangement  seems  to  have  been  that  Houdin  had  found 
his  mare  being  underfed  by  a  former  hostler,  who  con- 
verted as  much  food  as  possible  into  hard  cash  for  his 
own  behoof.  In  order  to  prevent  the  hostler  remaining 
in  the  stable  while  the  horse  was  fed,  the  oats  were  only 
allowed  to  fall  into  the  trough  while  the  stable  door  was 
shut  and  locked,  and  he  could  not  remain  in,  as  he  could 
only  lock  the  door  from  the  outside.  The  man  could 
not  re-enter  while  the  oats  were  in  the  manger  without 
his  master  being  informed  of  the  fact,  for  if  the  door  was 
opened  before  the  oats  were  finished  a  signal  was  given 
in  the  house. 

The  power  for  ringing  some  bells  in  the  tower  was 
stored  in  a  most  ingenious  way,  for  between  the  kitchen 
situated  on  the  ground  floor  and  the  clockwork  in  the 
garret  there  was  a  contrivance  so  arranged  that  the 
servants  in  going  to  and  fro  about  their  work  wound  up 
the  weights  without  being  conscious  of  it.  The  ringing 
of  these  bells  was  electrically  controlled  by  the  study 
clock,  which  also  operated  time  dials  in  several  rooms. 

If  Houdin  desired  dinner  earlier  he  simply  pressed  a 
button  in  the  study  and  put  the  kitchen  clock  forward 
a  quarter  of  an  hour.  The  same  clock  switched  on  con- 

297 


AN  EXTRAORDINARY  MANSION 

tinuous  ringing  alarms  to  waken  the  servants  in  the 
morning. 

Houdin  evidently  had  his  greenhouses  connected  with 
his  study  by  thermo-electric  apparatus,  for  he  would 
surprise  his  gardener  by  saying,  "Jean,  you  had  too 
much  heat  last  night ;  you  will  scorch  my  geraniums,""  or 
"  Jean,  you  are  in  danger  of  freezing  my  orange-trees." 

The  house  was  fitted  with  automatic  electric  fire-alarms 
and  burglar-alarms,  the  latter  being  switched  on  to  every 
door  and  window  at  the  hour  of  midnight  by  the  study 
clock,  and  again  disconnected  by  the  clock  in  the  morning. 

It  is  probably  almost  half  a  century  since  this  wonder- 
ful mansion  was  thus  equipped.  I  have  found  no  means 
of  learning  exactly  when  Houdin  retired  and  went  to  live 
in  it,  but  it  is  certain  that  he  was  using  electro-magnetic 
apparatus  to  aid  him  in  stage  effects  in  Paris  during  the 
year  1845,  at  which  date  we  consider  electricity  to  have 
been  in  its  early  infancy. 


298 


CHAPTER    XXX 
HOW   WE  MEASURE   ELECTRICITY 

Our  present  primitive  methods  of  measuring  material  things— No 
artificial  standards  in  electricity— A  most  eccentric  genius  does 
much  to  aid  electrical  progress — How  the  electrical  units  were  named 
— An  absent-minded  philosopher — An  explanation  of  the  units — 
How  the  pressure  and  rate  of  flow  are  measured— How  the  con- 
sumption is  measured — The  earliest  consumption  meter— How 
a  modern  electric  meter  works — A  clumsy  method  of  paying  for 
energy,  and  an  exact  electrical  method. 

TO  measure  any  material  thing  is  an  easy  matter,  for 
we  may  compare  it  with  some  other  known  object. 
One  may  say  that  a  thing  is  so  many  times  longer 
or  heavier  than  a  certain  other  thing,  which  we  agree  to 
take  as  a  standard.     Some  of  the  earliest  "  standards " 
used  were  the  finger,  the  hand,  the  forearm  (cubit),  the 
foot,  the  span,  the  stride,  the  mile  of  one  thousand  paces, 
and  so  on. 

Early  in  the  fourteenth  century,  about  ten  years  after 
the  Battle  of  Bannockburn,  it  was  agreed  that  "three 
grains  of  barley,  dry  and  round,  do  make  an  inch,"  and 
"  twelve  inches  make  one  foot."  Even  now  our  methods 
are  entirely  artificial,  although,  fortunately,  more  definite 
than  these  primitive  "  standards." 

It  would  seem  very  primitive  indeed  if  our  legislators 
merely  made  two  chalk  marks  on  the  floor  of  the  House 

299 


METHODS   OF  MEASURING 

of  Commons,  and  then  informed  us  that  the  distance 
between  these  two  marks  must  be  reckoned  a  foot  or 
a  yard,  or  any  other  name  they  cared  to  give  it ;  but  in 
point  of  fact  our  present  method  is  really  just  as  primitive, 
except  that  we  have  taken  care  to  preserve  the  marks  for 
future  reference.  We  have,  locked  up  at  the  Standards 
Office  in  London,  a  bronze  bar  thirty-eight  inches  long, 
having  two  gold  studs  sunk  into  the  bar  near  its  ends,  on 
both  studs  a  line  is  cut,  and  the  distance  between  these 
two  parallel  marks  is  the  length  we  have  agreed  to  call 
the  yard,  but  in  order  to  be  as  exact  as  possible  the 
measure  must  be  made  when  the  metal  bar  is  at  a  tem- 
perature of  62°  Fahrenheit.  All  other  lineal  measures  are 
either  smaller  parts  or  multiples  of  this  definite  but 
artificial  standard.  The  unit  of  weight  is  the  pcund,  and 
this  is  defined  by  a  certain  piece  of  platinum  also  pre- 
served in  the  Standards  Office.  Four  copies  of  these 
standards  are  deposited  in  other  places  of  safety,  in  case 
of  any  accident. 

The  French  have  attempted  a  more  natural  standard  of 
length,  in  taking  the  "  metre  "  as  one  ten-millionth  part 
of  the  quadrant  of  the  earth  through  Paris ;  but  this  is 
not  absolutely  correct,  so  the  French  have  their  standards 
preserved  in  their  capital,  just  as  we  have. 

On  visiting  the  Bank  of  England  one  finds  that,  instead 
of  counting  the  sovereigns,  an  official  desiring  to  fill  a  bag 
with,  say,  £1,000,  simply  weighs  out  a  certain  weight  of 
sovereigns  as  though  he  were  weighing  sugar.  This  is, 
of  course,  a  perfectly  reliable  method  as  the  scales  are 
very  sensitive,  and  he  already  knows  by  experience  that 
one  thousand  sovereigns  weigh  a  certain  amount,  so  he  is 

300 


By  permission  of]  [Siemens-Schuckert  Werke,  Berlin. 

A  Shock-proof  Overall  invented  by  Professor  Artemieff  for  use  in  Laboratories  in  which  electricity 
at  very  high  potentials  is  employed.  The  electrician  is  working  among  these  high-tension 
currents  without  any  fear  of  shock.  The  overall  is  made  of  fine  metal  gauze  and  com- 
pletely envelops  the  electrician  from  head  to  foot.  In  the  picture  it  is  only  visible  over 


the  head  and  hands. 


NO  ARTIFICIAL   STANDARDS 

confident  that  if  he  gets  the  weight  correct  he  will  have 
the  number  of  sovereigns  also  correct.  The  number  of 
coins  is  here  arrived  at  by  the  weight,  or  in  other  words 
by  the  effect  of  gravity  upon  the  mass  of  the  coins. 

We  measure  heat  by  its  expansive  effect  upon  a  column 
of  mercury  or  spirit,  or  by  its  electrical  effect,  as 
explained  in  an  earlier  chapter,  and  in  a  similar  fashion 
we  measure  electricity  by  its  effects. 

In  previous  chapters  we  have  noted  the  magnetic  effect 
produced  by  a  current  flowing  in  a  coil  of  wire,  and  as 
the  magnetic  effect  is  in  proportion  to  the  amount  of  the 
controlling  current,  we  have,  in  this  effect,  an  exact  means 
of  measurement,  and  most  electrical  measuring  instru- 
ments are  based  upon  this  magnetic  effect. 

If  we  take  a  coil  of  wire  and  suspend  a  magnetic  needle 
in  it,  we  find  the  magnet  deflected  more  and  more  as  the 
current  increases,  but  the  amount  of  movement  will,  of 
course,  be  also  dependent  on  the  size  of  the  coil,  the 
number  of  its  turns,  etc.,  so  where  are  we  to  find  a  con- 
venient standard  to  lock  up  ?  It  is  fortunate  we  do  not 
require  to  base  our  electrical  units  upon  any  artificial 
standard,  as  we  do  for  our  measures  of  length  and  weight. 

When  electricity  came  to  be  used  in  everyday  life  it 
was  found  necessary  to  have  a  definite  measure  to  refer  to, 
for  it  would  not  do  merely  to  record,  as  some  early  ex- 
perimenters did,  that  the  current  required  for  a  certain 
result  was  such  that  it  dashed  the  needle  of  his  largest 
galvanometer  against  its  stops,  and  so  on.  About  forty 
years  ago  it  became  quite  evident  that  a  great  deal  would 
depend  in  the  practical  applications  of  electricity  upon 
having  a  proper  system  of  measurements.  With  this  in 

301 


A  MOST  ECCENTRIC   GENIUS 

view  the  "British  Association  for  the  Advancement  of 
Science"  appointed  a  committee  of  scientific  men,  with 
Sir  William  Thomson  (Lord  Kelvin)  as  its  leading  light, 
to  suggest  suitable  standards  of  electrical  measure- 
ment. It  is  not  within  the  scope  of  this  book  to  show 
how  these  absolute  units  were  arrived  at,  and  indeed 
a  statement  of  the  facts  would  not  interest  those  who 
have  not  already  gained  a  certain  amount  of  scientific 
knowledge,  but  I  think  it  will  be  of  interest  to  the 
general  reader  to  know  how  electricity  is  measured  by 
these  fixed  units. 

We  have  already  seen  in  chapter  viii.  the  great  amount 
of  money  lost  in  the  early  submarine  cables,  which  were 
not  capable  of  doing  the  work  required  of  them,  and  the 
true  explanation  of  this  unnecessary  waste  seems  clearly 
to  lie  in  the  fact  that  at  that  time  there  did  not  exist  any 
proper  electrical  measurements. 

It  is  of  interest  in  passing  to  note  that  a  great  deal  of 
credit,  in  connection  with  a  basis  of  electrical  measure- 
ments, is  due  to  the  individual  labours  of  a  rather 
eccentric  gentleman,  the  Honourable  Henry  Cavendish,  a 
nephew  of  the  third  Duke  of  Devonshire.  Cavendish  was 
a  great  genius,  and  he  contributed  much  of  value  to 
many  branches  of  science.  Having  plenty  of  this  world's 
wealth  he  used  to  shut  himself  up  in  his  laboratory  and 
busy  himself  day  after  day  experimenting,  from  a  true 
love  of  science.  He  was  in  the  habit  of  lending  books 
from  his  library  to  any  man  of  science  known  or  recom- 
mended to  him,  and  in  connection  with  this  it  is  sur- 
prising to  find  that  he  was  so  methodical  that  he  never 
took  down  a  book  for  his  own  use  without  entering  it  in 

302 


ELECTRICAL   UNITS 

the  lending  register.  I  say  that  one  is  surprised  to  learn 
of  this  methodical  plan,  for  it  is  a  known  fact  that  this 
great  genius  was  very  careless  in  recording  his  scientific 
results,  often  merely  jotting  them  down  on  the  backs  of 
old  envelopes  or  other  loose  scraps  of  paper,  and  though  a 
publication  of  his  researches  was  made,  after  a  lapse  of 
some  eighty  years,  by  Clerk-Maxwell,  there  doubtless 
must  have  been  many  interesting  facts  never  made  known. 
Cavendish  was  so  devoted  to  his  hobby  that  society  had 
no  attractions  for  him  ;  he  only  met  his  heir  once  a  year, 
he  himself  being  a  bachelor,  and  all  his  intercourse  with 
the  outer  world  may  be  summed  up  in  his  attendance  at 
the  meetings  of  the  Royal  Society,  and  dining  with  its 
members  once  a  week.  Any  instructions  to  his  servants 
he  wrote  down  and  left  in  a  note  on  his  hall  table,  while 
his  maidservants  were  ordered  to  keep  out  of  his  sight  on 
pain  of  dismissal. 

The  British  Association  Committee  decided  to  name  the 
electrical  units,  agreed  upon,  after  the  great  men  of 
science  who  had  done  so  much  towards  the  advancement 
of  the  science ;  and  it  seems  to  me  a  pity  that  the  name  of 
Cavendish  was  not  memorialised  in  some  form,  although 
it  is  sure  to  be  kept  in  remembrance  by  all  students  of 
physics. 

The  unit  of  pressure,  or  electro-motive  force,  has  been 
called  the  "  volt,"  after  Volta,  who  discovered  the  flow  of 
electricity  between  two  dissimilar  metals  in  contact, 
which  discovery  led  to  the  construction  of  batteries. 
The  unit  of  current,  or  rate  of  flow,  was  called  the 
"  ampere,"  after  the  great  French  scientist  of  that  name 

303 


EXPLANATION  OF  THE   UNITS 

who  suggested  the  galvanometer,  and  who  did  much  for 
the  science  of  electricity. 

This  great  physicist  was  said  to  have  been  at  all  times 
so  absorbed  in  his  work  that  his  wife  had  very  great 
difficulty  in  getting  him  out  of  his  laboratory  even  when 
he  had  some  important  appointment  to  keep.  The  story 
is  told  of  how  on  one  occasion,  when  he  and  Madame 
Ampere  were  to  attend  some  great  banquet,  his  wife  at 
last  succeeded  in  getting  him  away  from  his  experiments, 
and  upstairs  to  dress,  but  she  evidently  did  not  get  him 
away  from  the  problems  working  in  his  mind.  After 
waiting  impatiently  for  his  arrival  downstairs  in  evening 
dress  she  was  at  last  compelled  to  go  up  and  ascertain 
the  cause  of  delay,  and  one  can  well  imagine  her  dismay 
when  she  found  the  great  genius  sound  asleep  in  bed. 
His  mind  had  been  so  absorbed  that  coming  away  with 
the  intention  of  preparing  to  don  his  dress-suit  he 
automatically  went  to  bed,  and  having  doubtless  arrived 
at  a  satisfactory  solution  to  the  absorbing  problem,  fell 
into  a  pleasant  slumber. 

The  unit  of  electrical  resistance  was  called  the  "  ohm,* 
after  the  great  German  physicist,  Professor  Ohm,  who 
formulated  the  law  that  the  strength  of  ah  electric 
current  in  a  wire  depends  not  only  upon  the  electrical 
pressure  driving  it  through  the  wire,  but  also  upon  the 
amount  of  the  resistance  offered  by  the  wire  to  the 
passage  of  the  current.  While  we  are  not  to  think  of 
this  resistance  as  a  mechanical  friction,  yet  it  is  well  to 
fix  in  our  minds  that  this  resistance  is  an  inherent 
property  of  the  conductor  itself,  and  not  in  any  way 

304 


PRESSURE  AND  RATE  OF  FLOW 

dependent  upon  the  current  that  happens  to  be  flowing 
through  it. 

These  three  units — the  volt  for  pressure  or  electro- 
motive force,  the  ampere  for  the  rate  of  flow,  and  the 
ohm  for  resistance — are  the  three  practical  units  of  most 
common  use. 

We  all  have  a  fair  estimate  of  what  a  yard  or  a  pound 
is,  and  it  would  be  well  if  we  also  formed  some  concep- 
tion of  what  these  electrical  units  are  like.  Some  idea 
of  the  magnitude  of  a  volt  may  be  obtained  from  the 
statement  that  the  electric  pressure,  or  electro-motive 
force,  of  a  single  battery  cell  is  between  one  and  two 
volts. 

In  thinking  of  the  ampere  we  must  remember  that  it 
is  the  unit  of  flow  in  one  second  of  time,  just  as  one 
would  say  of  water,  so  many  gallons  per  minute.  It  is 
in  amperes  we  measure  the  current,  while  the  volts  merely 
indicate  the  pressure  at  which  the  current  is  supplied. 
We  may  think  of  an  ampere  as  being  the  current  re- 
quired to  make  an  ordinary  glow-lamp  bright,  but  this 
may  vary  from  one-third  of  an  ampere  to  three  amperes, 
according  to  the  thickness  of  the  carbon  filament  which 
the  current  has  to  heat.  In  an  arc-lamp  we  require  a 
rate  of  flow  of  from  ten  to  twenty  amperes.  Thus  the 
heating  of  a  wire  or  other  conductor  depends  on  the 
number  of  amperes  passing  through  it,  while  the  voltage 
will  be  determined  by  the  resistance  we  have  to  send 
the  current  through.  The  pressure  required  to  work  an 
arc-lamp,  with  the  great  resistance  offered  by  the  air 
space  between  its  carbon  points,  is  seldom  less  than  sixty 
volts,  whereas  a  small  glow-lamp,  with  its  continuous 
u  3°5 


MEASURING  INSTRUMENTS 

filament,  may  be  worked  with  as  low  an  electro-motive 
force  as  three  volts. 

It  only  remains  to  form  some  conception  of  the  ohm 
or  unit  of  electrical  resistance.  The  value  of  the  prac- 
tical ohm  is  very  conveniently  arranged,  so  that  it 
requires  a  pressure  of  one  volt  to  send  a  current  of  one 
ampere  through  the  resistance  of  one  ohm.  Here  we 
have  a  very  convenient  relationship  between  the  volt,  the 
ampere,  and  the  ohm,  for  if  we  know  the  value  of  any 
two  of  these  the  third  may  easily  be  found.  If  we  have 
a  circuit  of  two  ohms  resistance  and  we  have  a  source 
of  supply  at  six  volts  pressure,  then  we  know  that  the 
rate  of  flow  will  be  three  amperes,  for  each  volt  will 
cause  one  ampere  to  flow  through  one  ohm,  so  that  the 
six  volts  would  give  six  amperes  through  one  ohm,  but  as 
the  resistance  is  doubled,  i.e.  two  ohms,  then  the  six  volts 
will  only  get  the  current  to  flow  at  half  the  rate — viz. 
three  amperes.  We  may  count  the  value  of  the  practical 
ohm  to  be  the  resistance  of  one-third  of  a  mile  of  copper 
wire  about  one-tenth  of  an  inch  in  diameter,  or  one  may 
think  of  a  mile  of  ordinary  iron  telegraph  wire  as  having 
a  resistance  of  thirteen  ohms. 

It  will  be  clear  that  we  must  be  able  to  read  both  the 
pressure  and  the  rate  of  flow  ;  and  these  are  easily  in- 
dicated by  the  effect  of  the  current  in  passing  through 
a  coil  of  wire  in  which  a  magnetic  needle  is  pivoted.  To 
measure  the  pressure  we  have  a  voltmeter,  which  we  may 
consider  as  analogous  to  the  pressure  gauge  on  a  steam 
boiler;  and  to  measure  the  rate  of  flow  of  current  we 
have  an  ammeter  or  ampere  meter. 

Both  of  these  instruments  are  galvanometers,  having 

306 


AN  ANALOGY 

a  coil  of  wire  with  a  magnet  at  its  centre,  or  some  other 
arrangement  based  on  this  principle.  In  general  appear- 
ance they  are  very  similar,  and  one  might  quite  imagine 
an  Irishman  saying  that  if  they  were  not  similar  they 
were  the  same.  In  point  of  fact  the  only  difference  is 
that  the  ammeter  has  a  coil  made  of  a  short  thick  wire, 
so  as  not  to  obstruct  the  rate  of  flow,  and  the  voltmeter 
has  a  long  coil  of  thin  wire  to  offer  a  great  resistance  to 
the  current. 

It  seems  rather  strange  that  both  the  pressure  and  the 
rate  of  flow  should  be  independently  measured  by  the 
effect  of  the  current  upon  a  neighbouring  magnet.  It  is 
difficult  to  find  an  adequate  analogy,  but  one^s  mind 
naturally  thinks  of  water,  and  so  perhaps  the  following 
picture  may  be  of  assistance.  If  we  imagine  a  pipe 
through  which  water  is  flowing  at  a  constant  rate,  we 
might  place  a  very  little  waterwheel  in  its  course  to 
indicate,  by  its  revolutions,  the  rate  of  flow  of  the  water. 
Again,  if  we  desired  to  find  its  pressure,  we  might  apply 
a  definite  friction  to  the  waterwheel,  so  that  it  would 
require  a  certain  amount  of  pressure  to  turn  the  wheel  at 
a  given  rate.  This  must  only  serve  as  a  rough  analogy, 
with  the  waterwheel  representing  the  magnet,  but  one 
can  see,  in  the  first  case,  the  water  left  as  free  as  possible 
to  turn  the  wheel,  which  corresponds  to  the  ammeter 
with  the  heavy  wire  allowing  the  current  to  pass  freely. 
Again,  in  the  second  case,  we  put  a  resistance  in  the  way 
of  the  water,  and  thus  measure  its  pressure  against  this 
obstruction,  which  in  some  degree  is  analogous  to  the 
voltmeter  in  which  we  place  a  definite  resistance  in  the 
form  of  a  long  coil  of  fine  wire. 

307 


EARLIEST   CONSUMPTION  METER 

It  is  unnecessary  to  describe  the  details  of  construction 
of  these  instruments,  as  these  particulars  may  easily  be 
understood  from  the  principle  just  explained.  The  dial 
of  the  ammeter  is,  of  course,  marked  off  in  amperes,  and 
the  voltmeter  in  volts. 

It  will  naturally  be  very  difficult  for  anyone  to  realise 
merely  by  reading  about  volts  and  amperes  what  these 
units  really  are ;  one  only  comes  to  realise  what  a  pound 
weight  or  a  yard  measure  is  by  repeated  use  of  these 
units. 

The  meter  which  will  interest  the  general  reader  most 
is  the  consumption  or  supply  meter.  The  first  current 
meter  was  invented  by  Edison,  and  many  may  remember 
its  appearance  at  the  Paris  Exhibition  of  1881.  This 
meter  was  based  on  the  chemical  action  produced  by  a 
current  passing  through  a  solution  of  copper  sulphate. 
It  was,  in  fact,  an  electro-plating  apparatus,  having  two 
pieces  of  copper  suspended  from  the  opposite  ends  of  a 
balanced  beam.  When  the  current  passed  from  No.  1 
copper  to  No.  2,  it  plated  the  latter  with  copper  taken 
from  the  solution  and  replenished  by  No.  1  copper.  As 
this  No.  2  copper  increased  in  weight,  with  the  copper 
plated  on  to  it,  it  depressed  that  end  of  the  balanced 
beam,  which  operated  a  counting  mechanism.  When  this 
end  of  the  beam  came  down  a  certain  distance  it  automa- 
tically switched  the  current  on  in  the  reverse  direction,  so 
that  it  passed  from  No.  2  copper  to  No.  1  copper,  plating 
the  latter  this  time,  which  in  turn  brought  the  beam 
down  on  the  other  side,  see-saw  fashion,  once  more 
operating  the  counting  mechanism,  and  again  reversing 
the  current.  In  effect  it  was  simply  a  means  of  counting 

308 


MODERN  ELECTRIC  METER 

how  often  the  current  was  able  to  carry  over  a  certain 
amount  of  copper  from  the  one  plate  to  the  other  alter- 
nately, and  as  the  ability  of  the  current  to  do  this  de- 
pended on  the  amount  of  current  passing,  a  direct  reading 
of  the  current  was  registered. 

This  gave  a  starting-point  for  inventors  of  supply 
meters,  and  to-day  forms  the  basis  of  some  modern 
meters,  although  in  itself  it  was  not  a  very  efficient  meter, 
owing  to  its  having  to  work  at  a  variety  of  temperatures, 
which  affected  the  conductivity  of  the  liquid.  It  would 
not  be  of  sufficient  general  interest  to  trace  the  growth  of 
this  class  of  meter,  nor  even  to  describe  all  the  different 
principles  at  work.  I  think  it  will  be  enough  merely  to 
indicate  how  the  measuring  is  done  in  the  meters  in  most 
common  use. 

Many  people  are  curious  to  know  how  an  electricity 
meter  works,  although  they  may  never  bother  their  heads 
with  the  details  of  a  gas  or  water  meter.  There  is 
nothing  mysterious  about  these  meters  to  them,  for  they 
are  operated  by  substantial  matter  passing  through  them ; 
but  to  talk  of  measuring  electricity  seems  to  them  some- 
what mystifying.  All  electric  meters,  however,  are  merely 
means  of  registering  the  effect  of  the  current  upon  certain 
material  arrangements. 

The  most  prominent  and  most  useful  property  of  elec- 
tricity is  undoubtedly  its  effect  upon  a  magnet.  We  find 
this  property  being  made  use  of  in  dynamos,  motors, 
telegraphs,  telephones,  etc.,  and  so  it  is  natural  that  it 
should  also  be  used  as  a  measure  of  the  current.  The 
more  current  one  supplies  to  a  little  motor  the  quicker  its 
armature  spins  round,  so  that  with  a  delicately- adjusted 


A   CLUMSY  METHOD 

armature,  arranged  to  operate  a  counting  mechanism,  we 
have  a  reliable  current  meter,  with,  of  course,  more  detail 
of  construction  than  is  here  mentioned,  such  as  a  contriv- 
ance for  reducing  the  speed  and  yet  keeping  the  revolu- 
tions proportional  to  the  variations  in  the  current  passing 
through  the  meter. 

We  ourselves  expend  a  great  deal  of  energy  every  day 
in  moving  about  and  performing  our  daily  tasks,  and  we 
require  to  lay  in  a  fresh  stock  of  energy,  which  we  do  by 
eating  nourishing  foods.  When  we  buy  food,  it  is  really 
the  energy  in  the  food  that  is  of  first  importance  to  us, 
whether  we  so  consider  it  or  not.  Paying  for  food,  how- 
ever, is  a  very  clumsy  method  of  paying  for  energy ;  for 
we  often,  wittingly  or  unwittingly,  pay  for  and  consume 
foodstuffs  that  add  very  little  energy  to  our  human 
mechanism ;  and  how  often,  owing  to  the  hurry-scurry  of 
life,  do  we  fail  to  extract  the  available  energy  from  our 
food.  The  point  I  desire  to  enforce  is  that  while  we  have 
here  a  very  roundabout  way  of  paying  for  energy,  we  have 
a  very  direct  and  exact  method  in  the  electric  meter. 

It  is,  of  course,  the  energy  of  the  electric  current  that 
we  desire  to  measure,  and  therefore  we  must  have  a  suit- 
ably arranged  unit  to  work  with  in  practice.  We  have  a 
dynamo  giving  out  a  certain  current  at  a  certain  pressure, 
according  to  the  construction  of  the  machine  and  the 
speed  at  which  its  armature  is  revolving,  so  that  the 
energy  available  will  be  the  quantity  of  current  passing  in 
a  given  time  multiplied  by  the  pressure.  The  unit  for 
this  might  be  termed  a  volt-ampere — one  volt  multiplied 
by  one  ampere ;  but  it  is  more  conveniently  called  a  watt, 
in  honour  of  James  Watt,  the  inventor  of  practical  steam- 

310 


EXACT  ELECTRICAL  METHOD 

engines.  This  unit  is  too  small  to  be  convenient,  so  elec- 
tricians have  adopted  one  thousand  watts  as  a  commercial 
unit  of  power,  and  have  named  this  a  kilowatt.  It  is 
clear  that  this  is  only  a  measure  of  the  power  or  capability 
of  the  current,  and  the  energy  the  consumer  can  get  from 
it  depends  on  how  long  he  can  get  the  use  of  this  amount  of 
power ;  and  so  the  Board  of  Trade  has  arranged  that  the 
unit  is  to  be  a  kilowatt  for  an  hour,  sometimes  called  a 
kilowatt-hour,  but  better  known  as  a  Board  of  Trade  unit, 
written  B.T.U.  If  the  charge  is  sixpence  per  B.T.U.,  it 
simply  means  that  the  consumer  is  to  get  the  use  of  a 
power  equivalent  to  one  thousand  watts  for  an  hour,  and 
for  this  he  is  to  pay  sixpence.  Of  course  he  may  spread 
the  using  of  this  kilowatt  over  any  length  of  time  he 
desires ;  he  may  use  it  at  the  rate  of  one  hundred  watts  in 
one  hour,  in  which  case  he  may  continue  using  that 
amount  of  power  for  ten  hours,  and  then  he  has  taken  the 
B.T.U.  his  meter  will  have  registered,  and  at  the  settling 
of  accounts  he  has  to  hand  over  the  required  money  value 
to  the  supplier. 

It  is  well  that  the  consumer  should  form  some  definite 
conception  of  what  he  can  get  from  one  B.T.U.  A 
sixteen-candle-power  lamp  is  estimated  to  consume  sixty 
watts,  so  that  he  should  be  able  to  have  that  lamp  alight 
for  about  16J  hours,  at  the  cost  of  one  B.T.U.  It  is 
also  well  that  he  should  fix  in  his  mind  how  a  B.T.U.  is 
made  up,  for  there  often  seems  to  be  quite  an  unnecessary 
vagueness  upon  this  point.  The  Board  of  Trade  unit,  as 
already  stated,  is  a  power  of  one  thousand  watts  for  one 
hour,  one  watt  being  one  volt  multiplied  by  one  ampere. 
He  may,  if  he  so  prefers,  remember  the  B.T.U.  as  one 

711 


EXACT   ELECTRICAL   METHOD 

thousand  volt-amperes  per  hour,  so  that  he  knows  if  his 
current  is  being  supplied  at  a  pressure  of  one  hundred 
volts  then  he  is  consuming  ten  amperes  in  his  Board  of 
Trade  unit.  It  may  be  noted  in  passing  that  one  thousand 
watts  is  approximately  equal  to  one  and  one-third  horse 
power. 

Some  readers,  to  whom  the  subject  has  been  quite 
new,  may  still  be  a  little  puzzled  as  to  the  meaning 
of  the  ampere.  The  other  units  seem  to  be  more  easily 
grasped  than  this  one,  but  I  think  the  difficulty 
arises  from  an  omission  to  remember  that  the  ampere 
is  not  really  a  measure  of  quantity,  but  is  a  rate  of  flow, 
or  current  strength.  The  measure  of  electric  quantity 
is  really  the  coulomb,  called  after  a  great  French  physicist, 
who  lived  during  the  French  Revolution.  A  coulomb  is 
the  quantity  of  electricity  required  to  produce  a  definite 
chemical  effect,  to  deposit  1/1183  milligrammes  of  silver. 
An  ampere  is  the  rate  of  flow  of  a  steady  current  of  one 
coulomb  per  second,  just  as  one  may  speak  of  a  flow  of 
water  being  at  the  rate  of  one  gallon  per  minute.  If  we 
had  one  single  word  to  represent  the  phrase  "  one  gallon 
per  minute,1''  then  we  should  have  a  corresponding  word 
referring  to  the  rate  of  flow  of  water,  just  as  we  have 
the  single  word  "  ampere  "  to  represent  the  rate  of  flow 
of  electric  current. 

To  be  told  that  water  is  flowing  through  a  pipe  at  the 
rate  of  so  many  gallons  per  minute  does  not  indicate 
the  quantity  of  water  that  has  passed  until  one  knows 
for  how  many  minutes  or  hours  the  water  has  been  flow- 
ing. In  a  similar  manner  if  we  are  given  the  rate  of  flow 
of  a  current  in  amperes,  we  must  also  know  the  duration 

312 


EXPLANATION   OF   THE   AMPERE 

of  the  flow  before  we  can  tell  what  quantity  has  passed. 
A  two-ampere  current  will  have  conveyed  in  one  hour 
7,200  coulombs,  which  figure  is  simply  calculated  as  2 
amperes  x  60  seconds  x  60  minutes.  If  we  have  a  current 
strength  of  only  one-tenth  ampere,  then  it  will  take  ten 
seconds  of  flow  before  one  coulomb  has  passed. 

Speaking  of  a  waterwheel,  we  may  say  that  we  require 
a  flow  of  so  many  gallons  per  minute  to  drive  it,  and  in 
the  same  way  we  may  say  that  we  require  a  current  of 
so  many  amperes  to  keep  the  filament  of  an  electric  light 
glowing.  The  general  reader  is  constantly  coming  across 
the  word  ampere,  but  he  stldom  meets  the  word  coulomb, 
as  it  is  included  in  the  word  ampere,  the  meaning  of 
which,  as  already  pointed  out,  is  a  rate  of  flow  of  one 
coulomb  per  second. 

It  is  obvious  that  if  there  is  a  fixed  pressure  or  voltage 
one  can  vary  the  rate  of  flow,  that  is,  the  amperes,  by 
altering  the  amount  of  resistance  in  the  path  of  the 
current,  just  as  one  does  in  drawing  water  off  the  main 
through  an  ordinary  stop-cock.  The  further  one  draws 
the  stop-cock  out  of  the  pipe  the  greater  the  rate  of 
flow,  and  the  greater  resistance  one  leaves  in  the  path 
of  the  water  the  smaller  is  the  rate  of  flow.  As  already 
explained,  the  electrician  places  coils  of  various  thicknesses 
of  wire  in  the  path  of  the  electric  current,  and  in  this  way 
he  is  able  to  regulate  the  current  strength.  If  we  wish 
to  maintain  the  same  rate  of  flow  (amperes)  through  an 
increased  resistance  (ohms),  then  we  must  increase  the 
pressure  (volts).  We  already  saw  that  it  requires  one 
volt  of  pressure  to  drive  a  current  of  one  ampere  strength 
through  a  resistance  of  one  ohm,  it  will  therefore  require 


EXPLANATION   OF   THE   AMPERE 

a  pressure  of  two  volts  to  send  the  same  current  through 
a  resistance  of  two  ohms.  If  we  had  left  the  pressure  at 
one  volt  and  still  increased  the  resistance  to  two  ohms, 
then,  of  course,  the  rate  of  flow  would  have  been  only 
half  its  original,  or  half  an  ampere. 

While  the  ampere  indicates  the  rate  of  flow,  it  is  plain 
that  if  a  current  of  one  ampere  be  allowed  to  flow  for 
one  hour,  then  we  have  a  definite  quantity  of  electricity, 
which  we  term  an  ampere-hour.  It  requires  a  certain 
pressure  to  send  this  current  through  the  circuit,  depen- 
dent upon  the  resistance  offered.  If  an  ampere-hour  be 
multiplied  by  the  pressure  (volts),  then  we  have  the  con- 
sumption of  electrical  energy  in  watt-hours,  one  thousand 
of  which  are  called  a  Board  of  Trade  unit. 


CHAPTER  XXXI 
SOME   QUESTIONS   ANSWERED 

The  meaning  of  positive  and  negative  electricity— How  to  tell  in 
which  direction  a  current  is  flowing — An  amusing  conversation — 
The  current  that  kills — The  resistance  of  the  human  body. 

THERE   are  a  great  many  points    of   importance 
which  I  have  deemed  it  inadvisable  to  touch  upon 
in  the  foregoing  chapters  because,  to  many  readers, 
these  would  doubtless  seem  dry  and  uninteresting.     It  is, 
however,  probable  that  in  the  minds  of  some  readers  there 
will  be  a  desire  for  further  explanation,  and  so  I  have 
thought  it  well  to  devote  this  chapter  to  answering  such 
questions    as    might    naturally    arise.     These    few    pre- 
liminary words  will  serve  to  mark  this  chapter  as  intended 
only  for  the  latter. 

I  think  the  first  question  would  probably  be  regarding 
positive  and  negative  electricities,  the  mention  of  which 
has  been  so  scrupulously  avoided  in  the  whole  of  the  pre- 
ceding chapters.  These  are  merely  arbitrary  terms,  but 
they  serve  a  very  useful  purpose,  and  part  of  the  forego- 
ing explanations  might  possibly  have  been  made  simpler 
by  the  use  of  these  terms,  but  my  experience  has  been 
that,  to  many  people,  these  and  kindred  terms  are  rather 

3'5 


DIRECTION   OF   CURRENT 

a  worry:  hence  my  avoidance  of  them.  These  terms  of 
positive  and  negative  originated  with  the  one-fluid  theory 
of  electricity,  in  which  the  +  sign  was  used  to  indicate  an 
excess  of  the  supposed  fluid  and  the  -  sign  a  deficiency, 
the  earth  being  taken  as  zero,  or  we  might  say  as  the 
electrical  sea-level.  These  terms  have  really  no  connec- 
tion now  with  the  idea  of  more  and  less.  We  have  direct 
evidence  that  there  are  two  distinct  kinds  of  electricity. 

The  general  reader  will  be  interested  in  these  terms 
in  their  connection  with  electric  currents  rather  than 
as  regards  electrified  bodies,  so  I  will  merely  deal  with 
them  in  the  former  connection.  We  form  a  mental 
picture  of  the  electric  current  flowing  from  the  positive 
pole  of  a  battery  or  dynamo  round  the  circuit,  through 
the  lamps,  etc.,  and  back  to  the  negative  pole.  In  a 
simple  battery  cell  we  speak  of  the  current  passing  from 
the  carbon  connection  through  the  connecting  wire  to  the 
zinc  element,  and  so  we  call  the  carbon  the  positive  pole 
and  the  zinc  the  negative  pole.  In  a  dynamo  the  position 
of  the  poles  is  according  to  the  direction  of  winding  the 
coils. 

It  is  easy  to  discover  in  which  direction  a  current  is 
flowing  in  a  wire  by  its  magnetic  influence  on  a  neighbour- 
ing compass  needle.  If  the  wire  carrying  the  current 
be  placed  over  the  compass  needle,  which  is  pointing 
north  and  south,  and  when  the  current  passes,  the  needle 
turns  its  north  pole  to  the  east,  then  we  know  the  current 
is  flowing  in  the  direction  from  north  to  south.  Of  course 
the  magnetic  needle  need  not  be  placed  in  its  natural 
position  as  in  a  compass.  It  may  be  mounted  on  its 
centre  in  an  upright  position  at  the  back  of  a  dial,  as  in 

316 


AN  AMUSING  CONVERSATION 

a  galvanometer,  and  the  indicator  on  the  face,  moving 
with  the  magnet,  will  show  its  movements,  falling  to  one 
side  or  the  other  according  to  the  direction  in  which  the 
current  is  sent  through  the  coil  surrounding  the  magnet. 

It  was  recognised  by  some  of  the  earliest  workers  that 
there  were  two  distinct  kinds  of  electricity.  Later  workers 
departed  from  this  idea.  Indeed  it  is  not  so  long  since 
some  of  the  foremost  scientists  of  our  day  thought  for  a 
time  that  electricity  was  not  a  real  thing,  but  that  electric 
currents  and  electric  charges  were  merely  phenomena  in 
the  ether  of  space.  We  have  direct  evidence  now  that 
electricity  is  a  real  existing  thing. 

I  was  very  much  amused  in  overhearing  some  remarks 
which  passed  between  two  gentlemen  in  a  public  convey- 
ance. One  asked  the  other  how  it  was  that  a  person 
might  walk  along  the  rails  of  an  electric  tramway  and 
yet  not  receive  a  shock  from  the  dynamo  to  which  they 
are  connected.  His  friend's  reply  was  that  the  rails  only 
carried  negative  electricity,  which  was  quite  harmless,  and 
that  it  was  the  positive  electricity,  carried  by  the  trolley 
wire,  that  killed.  This  gentleman  would  doubtless  have 
been  surprised  if  he  had  been  told  that  a  tight-rope 
dancer  could  walk  along  the  trolley  wire  with  as  little 
fear  of  electrocution  as  upon  the  rails.  The  space 
between  the  overhead  wire  and  the  rails  is  just  like  a 
break  in  the  circuit  through  which  the  current  flows  from 
one  brush  of  the  dynamo  to  the  other.  When  the  car 
comes  along  it  closes  the  circuit,  allowing  the  current  to 
flow  down  the  trolley  pole,  through  the  motor,  and 
away  back  to  the  dynamo  by  the  rails.  If  a  person  gets 
in  contact  with  the  rails  and  the  overhead  wire,  owing  to 

317 


THE  CURRENT  THAT   KILLS 

the  falling  of  the  latter,  then  the  person  becomes  part 
of  the  electric  circuit,  and  receives  a  fatal  shock.  If  the 
person  is  not  on  the  rails,  but  on  the  ground,  when  the 
overhead  wire  touches  him,  he  will  undoubtedly  receive 
a  shock,  but  the  resistance  to  the  current  will  be  so 
much  greater  that  no  very  serious  injury  is  likely  to  be 
done. 

The  tramway  motor-men  are  supplied  with  rubber 
gloves  with  which  they  may  handle  a  live  wire  in  the 
event  of  its  coming  down.  Their  duty  is  to  place  the  end 
of  the  wire  on  one  of  the  rails,  whereupon  the  current  is 
given  such  an  easy  path,  allowing  so  great  a  rush  of 
current,  that  the  safety  devices  at  the  power-station  come 
into  action  and  automatically  cut  off  the  current. 

It  may  have  occurred  to  some  to  wonder  what  amount 
of  current  really  does  kill.  Even  nowadays  one  very 
occasionally  comes  across  some  elderly  lady  or  gentle- 
man who  fears  that  death  may  result  from  an  ordinary 
battery  current.  I  have  fallen  in  with  two  such  cases 
quite  recently,  but  with  the  widespread  use  of  electricity 
such  mistaken  ideas  cannot  survive  long  even  in  distant 
rural  districts.  Many  of  us,  when  youngsters,  were  in- 
formed that  birds  were  often  electrocuted  by  resting  on 
the  ordinary  telegraph  wires.  While  it  is  true  that  a 
great  number  of  birds  are  found  lying  dead  immediately 
below  telegraph  lines,  it  is  generally  known  now  that 
their  death  has  been  brought  about  by  sudden  collision 
with  the  wire,  against  which  they  have  accidentally  flown. 
Hence  the  little  pieces  of  wood  one  often  sees  fastened  to 
telegraph  wires  in  the  country  are  there  to  attract  the 
attention  of  the  birds  to  the  presence  of  the  wire.  From 

318 


RESISTANCE  OF  THE  HUMAN  BODY 

what  has  already  been  said  regarding  the  trolley  wires,  it 
will  be  clear  that  even  if  a  bird  were  to  rest  on  a  "  live " 
wire,  as  one  sometimes  does  see  on  a  country  road  along 
which  a  tramway  runs,  the  bird  receives  no  shock,  the 
bird  not  forming  part  of  an  electric  circuit. 

Even  now  one  often  finds  some  people  afraid  lest  they 
may  receive  a  fatal  shock  if  handling  the  connections  of 
an  ordinary  glow-lamp.  Of  course  this  is  impossible, 
and  yet  one  knows  that  fatal  shocks  may  be  received  from 
the  conductors  for  arc-lighting.  Where,  then,  is  one  to 
draw  a  distinctive  line?  The  current  supplied  for 
domestic  lighting  is  at  a  low  pressure,  which  cannot 
possibly  do  any  serious  hurt ;  but  it  is  not  entirely  a  case 
of  pressure,  for  a  person  may  receive  without  injury  a 
high-frequency  current  from  an  induction  coil,  etc.,  with 
a  pressure  of  many  thousands  of  volts.  In  the  case  of 
high-frequency  currents  the  amount  of  electricity  is  very 
small.  At  a  pressure  of  100,000  volts  the  current  may 
only  be  about  one-thousandth  part  of  an  ampere,  although 
I  have  seen  a  medical  friend  receive  as  much  as  one  two- 
hundredth  part  of  an  ampere,  or  five  milliamperes. 

The  current  that  will  pass  through  any  body  depends 
upon  the  resistance  it  offers,  as  well  as  the  pressure  of 
the  current  applied.  Fortunately  the  resistance  of  the 
human  body  is  very  high,  being  estimated  at  about  ten 
thousand  ohms,  but  if  a  person  grasp  two  metal  con- 
ductors the  resistance  from  one  hand  to  the  other  through 
the  body  may  only  be  from  one  to  three  thousand  ohms. 
If  some  vital  part  of  the  body  offer  one  thousand  ohms 
resistance  to  a  current  at  five  hundred  volts,  then  half  an 
ampere  current  will  pass  through  it,  and  this  may  be 

319 


RESISTANCE  OF  THE  HUMAN  BODY 

termed  a  current  that  kills.  I  know  of  a  recent  case 
where  a  workman  accidentally  touched  two  terminals  of 
a  machine  receiving  current  at  five  hundred  volts  and  he 
was  immediately  killed,  but  in  this  case  there  was  very 
little  resistance  offered  to  the  passage  of  the  current,  as 
the  man's  head  touched  both  terminals.  The  current  for 
domestic  purposes  is  supplied  at  a  pressure  of  about  two 
hundred  and  fifty  volts,  so  the  human  body  is  a  safe 
resistance  against  this  current.  There  is  no  doubt  that 
some  of  the  fatalities  from  electric  shock  are  really  due 
to  the  accompanying  nervous  shock. 

There  were  some  interesting  experiments  made  recently 
relative  to  the  conductivity  of  the  human  body,  and  it 
was  found  by  means  of  very  delicate  indicating  apparatus 
that  the  electrical  resistance  of  the  same  person  was 
continually  varying.  It  would  oscillate,  even  if  a  third 
person  entered  the  room  during  the  experiment,  and 
quite  a  marked  difference  was  obtained  by  a  change  of 
diet.  I  quote  two  results  which  were  given  in  a  con- 
tinental journal,  as  these  seem  of  interest  to  the  general 
reader:  "Any  sensation  or  psychical  emotion  of  some 
strength  will  reduce  instantaneously  the  resistance  of  the 
human  body  down  to  a  value  three  to  five  times  less." 
"  Nervous  persons,  as  well  as  heavy  smokers  and  drinkers, 
are  found  to  have  an  exceedingly  low  electric  resistance.'1 
The  first  of  these  two  quotations  seems  to  me  to  have 
a  definite  bearing  upon  fatal  shocks.  There  is  often  an 
alarming  display  of  flashes  when  a  conductor  breaks,  and 
in  this  way  the  normal  resistance  of  the  human  body 
may  be  very  greatly  reduced,  owing  to  unusual  alarm  and 
nervousness.  It  is  well  to  know  that  apparent  death 

320 


ELECTRIC  SHOCK 

from  electric  shock  is  sometimes  only  suspended  anima- 
tion, as  is  the  case  in  drowning,  so  that  artificial  re- 
spiration should  be  tried. 

One  used  to  hear  people  laying  stress  upon  the  great 
risk  accompanying  the  use  of  overhead  electric  wires  in 
connection  with  tramway  systems.  That  there  is  no  real 
cause  for  alarm,  provided  proper  care  is  taken,  is  evident 
from  the  experience  of  Glasgow.  This  great  centre  of 
industrial  activity  adopted  the  overhead  wire  system  in 
1900,  and  by  1910  there  was  in  use  about  one  hundred 
and  ninety  miles  of  overhead  wire.  During  all  these 
years  there  was  not  a  single  fatality  caused  by  the  break- 
down of  an  overhead  wire. 


321 


CHAPTER  XXXII 

WHAT   WE  KNOW  ABOUT 
ELECTRICITY 

What  is  electricity? — Some  questions  we  may  answer,  since  the 
discovery  of  " electrons" — What  is  matter? — What  is  an 
electric  charge  ? — What  is  an  electric  current  ? — The  difference 
between  a  continuous  and  an  alternating  current— What  is 
magnetism? — The  ether  of  space — What  is  light? — Discovery 
of  a  missing  link — What  is  heat  ? — What  is  chemical  union  ? 
— Importance  of  the  electron  theory. 


M 


ANY  years  ago  I  heard  one  workman  explain  to 
another  that  electricity  was  made  of  sulphuric 
acid  and  lead.  He  was  evidently  aware  that 
accumulators  contain  lead  plates  and  dilute  sulphuric 
acid,  and  he  knew  that  electricity  was  drawn  from  these 
accumulators  at  will,  therefore  it  seemed  to  him  as 
though  electricity  must  be  composed  of  these  substances. 
People  sometimes  twit  the  electrician  with  the  question 
"What  is  electricity?"  as  if  his  branch  of  science  was 
very  deficient  in  real  knowledge  compared  with  other 
departments  of  science.  If  the  questioner  is  asked  "What 
is  matter  ? "  he  will  no  doubt  realise  that  none  of  these 
very  simple-looking  questions  are  so  easily  answered.  It 
will  be  of  interest,  however,  to  see  how  far  we  have 
succeeded  in  explaining  the  mysteries  of  electrical 

phenomena. 

322 


QUESTIONS  WE  MAY  ANSWER 

Suppose  you  were  asked  "  What  is  water  ?  "  you  might 
reply  that  it  is  built  up  of  very  small  particles  or  mole- 
cnles  of  water,  each  of  which  is  composed  of  two  atoms 
of  the  gas  hydrogen  and  one  of  oxygen.  In  the  same 
manner,  we  believe  we  may  answer  the  questions  What  is 
matter? — What  is  an  electric  charge? — What  is  an 
electric  current  ? — What  is  magnetism  ? — What  is  light  ? 
— What  is  heat  ?  and  so  on.  Some  of  these  questions 
may  seem  to  have  no  direct  connection  with  the  subject 
of  electricity,  but  we  shall  see  that  a  very  intimate 
relationship  does  exist  in  each  case. 

When  electricity  at  high  tension  from  an  induction 
coil  was  passed  through  a  vacuum  tube,  such  as  has  been 
described  in  connection  with  X-ray  work,  it  was  found 
that  a  stream  of  flying  particles  was  shot  across  the  tube 
from  one  electrode  to  the  other.  At  first  it  was 
supposed  that  these  flying  particles  must  be  atoms  of 
matter,  but  later  it  was  proved  that  these  particles  were 
not  matter.  They  are  far  smaller  than  the  invisible 
atoms  of  matter.  Scientists  were  forced  to  the  conclusion 
that  these  were  particles  of  electricity  and  they  were 
christened  "  electrons,"  after  the  Greek  word  for  amber. 

A  great  deal  of  attention  was  directed  towards  these 
electrons,  which  some  have  preferred  to  call  corpuscles. 
It  was  found  that  those  particles  of  electricity  were 
always  of  the  kind  called  negative.  It  will  be  re- 
membered that  from  the  early  days  it  was  evident  that 
there  were  two  distinct  kinds  of  electricity,  although  it 
was  a  single-fluid  theory  that  suggested  the  names  positive 
and  negative.  We  have  definite  proof  that  negative 
electricity  is  made  up  of  small  particles,  just  as  matter  is 

323 


WHAT   IS   MATTER? 

molecular  in  nature.  We  have  no  definite  evidence  as  to 
the  nature  of  positive  electricity,  but  the  discovery  of  the 
negative  particles  has  opened  up  a  whole  world  of  new 
interests  to  us. 

We  believe  the  atoms  of  matter  to  be  composed  of 
little  congregations  of  these  electrons.  We  picture  each 
atom  as  a  miniature  solar  system ;  a  group  of  electrons 
revolving  at  enormous  speeds.  Of  course,  electrons  being 
little  particles  of  negative  electricity  would  all  tend  to 
fly  away  from  one  another,  just  as  any  two  similarly 
electrified  bodies  will.  We  therefore  picture  a  counter- 
part of  positive  electricity  in  each  atom,  but  what  form 
it  takes  we  cannot  determine.  Until  recently  it  was 
common  to  picture  the  electrons  revolving  within  a  tiny 
sphere  of  positive  electricity.  Now  it  seems  likely  we 
shall  find  positive  electricity  to  be  molecular  in  nature 
also.  In  other  words,  that  it  will  turn  out  to  be  composed 
of  particles,  which  although  much  larger  than  the  negative 
electrons,  are  still  infinitesimally  small. 

We  have  always  recognised  the  fact  that  an  atom  of 
gold  must  be  something  quite  different  from  an  atom  of 
lead  or  of  hydrogen  gas.  We  now  believe  the  real 
difference  to  be  due  to  the  number  of  electrons  which  com- 
pose it.  We  must  understand  that  these  revolving  electrons 
are  locked  up  within  the  atom.  We  cannot  interfere 
with  their  energy.  We  may  heat  the  substance,  composed 
of  the  atoms,  to  a  temperature  of  thousands  of  degrees, 
or  we  may  chill  it  down  till  its  temperature  reads  three 
hundred  degrees  below  zero  on  the  Fahrenheit  scale,  and 
yet  the  atoms  remain  as  before.  The  substance  will,  of 
course,  alter  from  a  solid  to  a  liquid  or  a  gaseous  condi- 

324 


WHAT   IS  AN  ELECTRIC  CHARGE? 

tion,  or  the  other  way  about  when  cooling.  But  an  atom 
of  gold  remains  always  an  atom  of  gold,  and  an  atom  of 
hydrogen  cannot  be  changed  into  anything  else.  Atoms 
have  been  called  the  little  bricks  of  nature.  The  electron 
theory  has  added  to  this  picture,  for  now  we  have  some 
idea  of  what  these  invisible  bricks  are  composed. 

In  very  rare  cases  we  see  evidences  of  an  atom  breaking 
up,  and  some  of  the  electrons  escaping  from  within  the 
atom.  The  most  notable  case  is  that  of  radium,  of  which 
we  read  in  an  earlier  chapter.  But  I  have  mentioned 
electrons  flying  across  an  X-ray  tube.  Where  did  these 
come  from  ?  It  is  quite  evident  that  they  cannot  come 
from  the  inside  of  the  atom ;  they  must  have  been 
outsiders.  We  have  ample  evidence  that  there  are  a 
great  many  electrons  which  are  attached  only  in  a 
temporary  manner  to  the  atoms  of  matter.  Indeed,  we 
picture  these  as  roving  electrons  wandering  about  from 
atom  to  atom. 

The  old-world  experiment  of  rubbing  a  piece  of  amber 
with  a  fur  or  cloth  has  a  new  interest  to  us.  We  have 
caused  a  surplus  of  these  roving  or  detachable  electrons  to 
leave  the  rubber  and  take  up  their  lodgment  upon  the 
amber.  We  have  added  so  many  little  particles  of  nega- 
tive electricity  to  the  amber  that  it  shows  an  appreciable 
negative  charge. 

A  body  charged  with  electricity  has  therefore  a  new 
meaning.  If  it  is  negatively  charged,  we  picture  a  surplus 
of  electrons  upon  its  surface.  There  must  of  necessity  be 
a  corresponding  deficiency  of  electrons  on  some  neighbour- 
ing body  or  bodies,  and  we  describe  this  condition  as 
positively  charged.  The  transfer  of  electrons  from  one 

325 


CONTINUOUS   CURRENT 

body  to  another  affects  the  surface  only.  Long  before  we 
knew  anything  about  electrons,  we  were  aware  that  an 
electric  charge  resided  only  upon  the  surface. 

When  we  speak  of  a  discharge  of  electricity,  such  as 
we  see  on  a  grand  scale  in  lightning,  we  picture  a  sudden 
expulsion  of  electrons  from  one  body  to  another.  In  the 
case  of  lightning  it  is  from  one  cloud  to  another,  or  be- 
tween a  cloud  and  the  earth. 

When  Volta  made  the  first  electric  battery,  he  caused 
the  atoms  in  the  zinc  plate  to  hand  electrons  along  the 
connecting  wire  to  the  atoms  in  the  copper  plate.  The 
electrons  were  handed  on  from  atom  to  atom  in  the  wire, 
each  atom  giving  up  a  spare  electron  to  its  neighbour  on 
one  side  as  it  accepted  an  electron  from  its  neighbour  on 
the  other  side. 

We  therefore  picture  a  steady  flow  of  electrons  along 
a  wire,  and  we  say  that  an  electric  current  is  flowing  in 
the  wire.  These  moving  electrons  disturb  the  ether  of 
space  surrounding  them,  and  the  energy  of  the  electric 
current  is  carried  really  by  the  ether.  It  is  well  to  take 
particular  note  of  this,  lest  any  one  should  imagine  that 
the  electrons  fly  along  the  wire  with  the  speed  of  the 
electric  current.  As  a  matter  of  fact,  the  rate  of  travel  of 
the  electrons  may  be  measured  conveniently  in  inches  per 
minute,  or  in  yards  per  hour.  The  action,  however,  com- 
mences simultaneously  along  the  whole  line. 

When  considering  dynamos,  we  saw  that  we  might  produce 
either  a  continuous  or  an  alternating  current  in  the  mains. 
In  the  former  case  we  set  up  a  regular  march  of  electrons 
from  atom  to  atom  along  the  line.  But  in  the  case  of  an 
alternating  current,  we  cause  the  electrons  to  surge  to-and- 

326 


THE  ETHER  OF  SPACE 

fro  from  atom  to  atom,  say  first  of  all  in  one  direction 
and  then  in  the  other.  Of  course  the  surrounding  ether 
will  be  disturbed,  and  energy  will  be  transmitted  just  as 
in  the  previous  case. 

In  addition  to  these  roving  electrons,  we  picture  others 
which  revolve  steadily  around  certain  kinds  of  atoms, 
particularly  the  atoms  of  iron.  These  moving  electrons 
produce  magnetism.  This  helps  us  to  extend  the  picture 
of  a  magnetic  body  which  we  considered  in  chapter  iv. 
But  if  moving  electrons  produce  magnetic  effects  in  the 
surrounding  ether,  we  should  expect  the  steady  flow  of 
electrons  along  a  wire  to  produce  magnetism  also.  We 
have  known  this  to  be  a  fact  for  nearly  a  century, 
although  no  reason  could  be  assigned  for  it.  It  was  a 
Danish  philosopher  who,  in  1819,  discovered  that  an 
electric  current  flowing  in  a  wire  set  up  a  magnetic  field 
around  it. 

Possibly  the  repeated  mention  of  this  ether  of  space 
is  rather  mystifying  to  some  readers.  The  nature  of  the 
ether  is  a  very  great  mystery  to  every  scientist.  This 
does  not  mean,  as  some  might  suppose,  that  the  ether  is 
not  a  real  existing  thing.  To  all  who  consider  the 
subject  seriously  it  is  as  real  as  the  air  they  breathe. 

It  would  be  better  if  we  agreed  to  spell  the  name  of 
this  mysterious  medium  aether  instead  of  the  much  more 
common  spelling  ether.  The  word  cether  seems  to  take 
us  farther  away  from  any  known  form  of  matter,  and  it  is 
quite  evident  that,  whatever  may  be  the  nature  of  the 
space-filling  medium,  it  is  not  any  form  of  ordinary 
matter.  One  theory  suggests  that  it  is  an  infinitely  light 
gas,  while  another  demands  for  it  a  density  greater  than 

327 


WHAT  IS   LIGHT? 

that  of  lead.  The  latter  theory  may  appear,  at  first 
sight,  to  be  quite  ridiculous.  But  if  we  picture  matter 
as  holes  in  a  very  dense  medium,  the  theory  is  not  incon- 
ceivable. However,  all  that  concerns  us  at  present  is 
that  although  the  nature  of  the  ether  is  a  complete 
mystery,  its  presence  is  very  real,  and  the  part  it  plays  in 
the  Universe  is  of  primary  importance. 

We  know  that  light  is  simply  waves  in  this  all-per- 
vading medium.  We  are  familiar  with  the  fact  that  a 
substance  when  heated  to  an  incandescent  state  will  set 
up  these  ether  waves  of  light.  Until  quite  recently  it 
was  a  mystery  to  us  how  atoms  of  matter  could  disturb 
the  ether,  for  it  is  apparent  that  even  huge  lumps  ot 
matter  such  as  the  planets  can  move  through  the  ether 
without  any  appreciable  resistance  being  offered  to  their 
movements. 

Here  we  are  on  the  back  of  a  great  planet  flying 
through  space  at  the  enormous  speed  of  one  thousand 
miles  per  minute,  and  the  ether  does  not  disturb  even  our 
flimsy  atmospheric  blanket,  which  we  carry  wrapped 
around  us  in  our  great  flight. 

The  electron  theory  supplies  the  missing  link  between 
the  ether  and  matter.  We  have  experimental  proof  that 
there  are  satellite  electrons  revolving  around  their  atoms 
just  as  the  Moon  revolves  around  our  Earth.  These 
satellite  electrons  make  billions  of  revolutions  per  second, 
and  in  doing  so  they  disturb  the  ether  and  produce  those 
waves  which  we  call  tight. 

If  these  satellite  electrons  revolve  at  a  comparatively 
slow  rate  they  produce  long  ether  waves  ;  in  other  words, 
waves  few  and  far  between.  These  waves  do  not  affect 

328 


WHAT   IS   CHEMICAL   UNION? 

our  vision,  but  they  produce  heat.  We  call  them  radiant 
heat  waves,  but,  of  course,  they  are  not  warm ;  they  are 
merely  waves  in  the  ether.  The  Sun  sets  up  such  waves 
and  they  reach  us  across  the  space  of  millions  of  miles, 
but  that  space  is  not  heated.  It  is  only  when  these  ether 
waves  fall  upon  matter  that  they  produce  the  phenomenon 
known  as  heat.  A  flying  bullet  on  the  battlefield  may 
produce  pain  when  it  strikes  a  soldier,  but  the  flying 
bullet  is  not  the  pain. 

When  the  satellite  electrons  revolve  at  a  speed  sufficient 
to  produce  the  short  waves  which  affect  our  eyes,  these 
waves  give  rise  to  a  variety  of  sensations.  A  certain  rate 
of  waves  produces  the  sensation  of  red,  a  higher  rate  gives 
rise  to  green,  while  a  still  higher  rate  stimulates  the 
violet  sensation.  When  all  these  waves  fall  upon  the 
same  part  of  the  retina  at  the  one  time,  we  have  that 
sensation  which  we  describe  as  white. 

Another  point  upon  which  the  electron  theory  has  shed 
new  light  is  the  nature  of  chemical  union.  We  have  no 
doubt  that  chemical  union  is  simply  electrical  union  be- 
tween the  atoms  of  matter.  It  is  really  a  case  of  electrical 
attraction  between  oppositely  charged  atoms.  This  adds 
a  new  interest  to  electro-chemical  actions.  We  see  how 
it  is  that  by  passing  an  electric  current  through  water,  we 
get  the  atoms  of  hydrogen  and  oxygen  to  part  company 
and  escape  as  oxygen  and  hydrogen  gases. 

We  have  answered,  in  some  measure,  the  questions  with 
which  we  set  out,  regarding  the  nature  of  matter,  electric 
charges,  electric  currents,  magnetism,  light,  and  heat.  It 
has  only  been  possible  to  draw  the  very  barest  outline  of 
the  electron  theory.  The  subject  is  so  large  that  to  give 

324 


THE  ELECTRON   THEORY 

even  a  popular  account  of  it  requires  a  volume  as  large 
as  the  present  one.  I  have  endeavoured  to  do  this  recently 
in  a  book  entitled  Scientific  Ideas  of  To-day*  That 
the  electron  theory  appeals  to  the  general  reader,  as 
well  as  to  the  scientist,  is  witnessed  by  the  fact  that  this 
popular  account  to  which  I  have  referred  has  gone  into 
a  third  edition  within  its  first  year.  Personally  I  believe 
that  the  electron  theory  is  the  beginning  of  a  new  era  of 
thought. 

*  Scientific  Ideas  of  To-day.     By  Charles  R,  Gibson.     Seelcy  and 
Co.  Ltd,,  London.    Five  Shillings  net. 


330 


CHAPTER  XXXIII 
CONCLUSION 

More  wonderful  than  Aladdin's  lamp— A  brief  historical  review — 
Slow  progress  prior  to  the  nineteenth  century — An  international 
advance— Davy  and  Faraday  —  A  genealogical  table — Present 
achievements— Future  possibilities. 

WE   have   seen   how   electricity  serves  mankind, 
enabling   us    to  hold  immediate   communica- 
tion with  all  parts  of  the  world;  or  carrying 
for  us   the   mighty  power   of  the   waterfall   to   distant 
towns   by  means   of  a  stationary  wire ;    or   making  it 
possible  for  us  to  actually  hold  conversation  with  friends 
distant  hundreds  of  miles.     Does  not  the  simple  state- 
ment of  these  and  similar  facts  read  as  a  fairy  tale,  and 
are  they  not,  in  truth,  far  more  wonderful  than  all  that 
Aladdin's  lamp  did  for  him  ? 

It  is  remarkable  that  all  the  practical  applications  of 
electricity  have  been  made  during  the  last  century,  and 
that  the  most  of  these  have  been  begun  during  the  life- 
time of  many  people  now  living.  Within  the  last  decade 
we  have  seen  many  new  fields  opened  up  in  the  electrical 
world,  the  most  conspicuous  applications  being  X-ray 
work  and  wireless  signalling.  The  experimental  work 
with  radio-active  bodies  has  also  a  close  connection  with 
electricity. 


BRIEF  HISTORICAL  REVIEW 

Electricity  had  been  known  from  early  times,  there 
being  records  relating  to  rubbed  amber  as  far  back  as 
640  B.C.,  and  the  discovery  of  magnetism  in  the  lodestone 
or  natural  magnet  is  a  matter  of  ancient  history,  having 
been  recorded  at  a  much  earlier  date  than  the  observed 
phenomena  of  electrical  attraction  in  rubbed  amber.  It 
does  seem  strange  that  these  phenomena,  which  have  now 
led  to  such  marvellous  results,  were  allowed  to  lie  prac- 
tically dormant  for  a  space  of  twenty  centuries.  During 
that  long  time  generations  of  men  came  and  went  attach- 
ing little,  if  any,  importance  to  these  great  discoveries, 
excepting  to  use  the  lodestone  as  a  guide  in  desert 
marches.  It  was  not  until  the  dawn  of  the  seventeenth 
century  that  any  serious  attention  was  given  to  this 
important  subject.  About  the  year  1600  Dr.  William 
Gilbert,  one  of  Queen  Elizabeth's  private  physicians, 
wrote  a  book  describing  many  experiments  he  had  made, 
and  deducing  from  these  that  the  earth  itself  was  a  huge 
magnet,  and  that  it  was  possible  to  magnetise  a  piece  of 
iron  by  the  earth's  influence.  Gilbert  also  suggested  that 
terrestrial  magnetism  and  electricity  were  both  allied 
emanations  of  a  single  force.  One  very  important  dis- 
covery of  Gilbert's  was  that  amber,  which  had  so  long 
been  known  to  possess  peculiar  properties  when  rubbed, 
had  no  monopoly  of  these  properties,  but  that  they  were 
also  exhibited  by  a  very  great  number  of  bodies  when 
rubbed.  By  direct  experiment  Gilbert  was  able  to  show 
such  bodies  as  glass,  sulphur,  sealing-wax,  hard  wood, 
etc.,  attracting  light  bodies  towards  them  after  friction 
had  been  applied  to  their  surfaces. 

But  although  Gilbert  wrote  down  very  clearly  in  Latin 
332 


AN  INTERNATIONAL  ADVANCE 

all  that  he  had  discovered  and  proved,  the  subject  received 
very  little  attention  for  another  century  and  a  half. 
During  that  time  people  had  certainly  taken  some  little 
interest,  for  they  had  constructed  simple  machines  to  do 
the  "rubbing"  for  them  on  a  larger  scale,  and  with  the 
increased  effects  a  few  additional  phenomena  had  been 
observed,  but  the  advance  of  knowledge  in  this  branch 
of  science  was  extremely  slow.  It  was  Germany  that 
gave  the  lead  in  the  making  of  these  early  electrical 
machines. 

About  the  middle  of  the  eighteenth  century  Benjamin 
Franklin,  the  great  American  philosopher,  discovered  the 
identity  of  electricity  with  lightning,  and  before  the 
century  had  closed  Professor  Galvani,  of  Italy,  made 
known  his  observations  on  the  twitching  of  a  dead  frog's 
legs  due  to  an  electric  discharge.  His  fellow  countryman, 
Volta,  a  celebrated  physician  of  Bologna,  in  following  up 
the  observations  of  Galvani,  discovered  a  means  of  pro- 
ducing a  continuous  electric  current.  Progress  now 
became  more  rapid,  for  with  the  dawn  of  the  nineteenth 
century  a  very  close  relationship  was  proved  to  exist 
between  electricity  and  magnetism.  We  are  indebted  to 
the  native  land  of  Her  Majesty  Queen  Alexandra  for  this 
very  important  discovery,  for  it  was  Hans  Christian 
Oersted,  of  Denmark,  who  observed  the  effect  of  an 
electric  current  upon  a  neighbouring  magnetic  needle. 
About  this  time  Professor  Ampere,  of  France,  and  Dr. 
G.  S.  Ohm,  of  Germany,  whose  names  are  embodied  in 
present-day  electrical  units,  did  much  to  make  the  mean- 
ing of  things  clearer.  It  was  also  about  this  same  time, 
or,  to  be  more  exact,  in  1822,  that  Professor  Seebeck,  of 

333 


DAVY  AND  FARADAY 

Berlin,  discovered  that  electricity  could  be  produced  by 
heat. 

While  it  was  an  Englishman  who  in  1600  laid  the 
foundations  of  electrical  science,  it  is  clear  that,  after  a 
long  lapse  of  years,  the  progress  was  very  materially  aided 
by  America,  Germany,  Italy,  France,  and  Denmark ;  but 
when  we  come  to  a  study  of  modern  developments  we  find 
two  Englishmen  taking  a  very  strong  lead.  Indeed,  we 
may  look  upon  Sir  Humphry  Davy  and  his  co-worker, 
Michael  Faraday,  as  the  pioneers  of  all  the  great  indus- 
trial applications  of  electricity.  These  two  great  men 
worked  together  at  the  Royal  Institution,  in  London, 
Faraday  acting  as  assistant  to  Davy.  It  is  interesting  to 
note  in  this  connection  that  although  Davy  was  only 
Faraday's  senior  by  a  dozen  years,  he  did  not  live  to  see 
any  of  the  great  electrical  industries  begun,  while  Fara- 
day, who  along  with  Davy  laid  the  foundation-stones, 
lived  to  see  many  electrical  applications  launched  on  a 
business  footing,  as  he  did  not  die  till  the  year  1867. 

There  is  an  interesting  story  told  of  Faraday,  which 
serves  to  show  his  very  practical  turn  of  mind.  An 
American  inventor  came  over  to  this  country  in  the  early 
days  of  electrical  enterprise,  exhibiting  a  large  electrical 
motor  machine,  with  the  object  of  floating  the  same  for 
industrial  purposes.  A  number  of  eminent  men  of  the 
day  were  asked  to  give  their  opinions  regarding  this  new 
kind  of  motor.  Some  gave  great  praise,  but  Faraday 
stood  for  some  time  watching  the  machine  at  work,  and 
then,  without  making  any  remark,  he  went  to  the  corner 
of  the  room,  and  picking  up  a  broom,  he  applied 
the  handle  of  it  as  a  brake  upon  the  large  fly-wheel 

334 


A  GENEALOGICAL  TABLE 

till  he  almost  brought  the  motor  to  a  standstill;  then, 
letting  it  go  free,  he  left  without  making  any  public 
statement.  It  must  have  been  clear  to  the  inventor  that 
his  motor  was  not  capable  of  driving  any  load.  Of 
course  this  genius  had  no  better  source  of  power  than  a 
large  and  clumsy  chemical  battery. 

This  review  has  purposely  been  very  brief,  and  is  there* 
fore  necessarily  incomplete,  including  merely  those  items 
of  most  general  interest.  A  very  simple  genealogical 
table  might  be  formed,  beginning  with  lodestone  and 
rubbed  amber,  the  latter  leading  to  the  construction  of 
frictional  machines ;  then  the  discovery  of  the  action  of 
one  of  these  machines  upon  the  legs  of  a  frog.  It  being 
found  that  the  contact  of  two  dissimilar  pieces  of  metal 
produced  the  same  twitching  effect  as  the  electrical 
machine,  a  battery  of  metal  discs  was  made,  and  these 
placed  in  acids  gave  us  the  principle  of  all  batteries.  The 
observed  effect  of  this  battery  current  upon  a  neighbour- 
ing magnetic  needle  gave  the  basis  of  all  telegraph  and 
telephone  apparatus,  and  when  it  was  discovered  that  the 
converse  was  true  and  that  a  magnet  could  so  influence  a 
moving  conductor  as  to  set  up  an  electric  current  in  it, 
then  dynamos,  motors,  induction  coils,  etc.,  soon  followed. 

Lord  Kelvin  (Sir  William  Thomson)  one  of  the  fore- 
most workers  in  the  electrical  world,  has  passed  away 
since  the  date  of  the  first  edition  of  this  volume.  His 
ingenuity  made  submarine  telegraphy  possible ;  he  added 
a  great  deal  to  our  electrical  knowledge.  Professor  Sir 
J.  J.  Thomson,  of  Cambridge,  and  Sir  Oliver  Lodge,  of 
Birmingham,  are  conspicuous  in  connection  with  modern 
ideas  of  electricity. 

335 


PRESENT  ACHIEVEMENTS 

To  sum  up  in  detail  the  benefits  we  have  already 
obtained  from  electricity  would  require  considerable  space, 
and  is  quite  unnecessary ;  it  will  be  sufficient  to  remark 
upon  a  few  of  the  principal  applications.  As  a  speedy 
carrier  of  news,  electricity  has  no  rival.  It  also  holds  a 
unique  position  in  transmitting  speech  over  great  dis- 
tances, and  quite  recently  we  have  the  almost  inconceiv- 
able achievement  of  speaking  through  space  without  any 
connecting  wires.  While  as  an  illuminant  electricity  has 
rivals  which  successfully  compete  with  it,  it  possesses 
many  advantages  over  its  competitors,  the  one  obstacle  to 
its  general  use  being  its  greater  cost.  As  a  means  of  con- 
veying power  from  one  place  to  another,  electricity  stands 
head  and  shoulders  above  all  other  methods,  making  it 
possible  to  take  advantage  of  the  energy  of  large  water- 
falls. We  have  seen  how  electricity  now  aids  the  physi- 
cian and  the  chemist,  whilst  a  host  of  other  interesting 
applications  have  been  dealt  with. 

It  would  be  idle  to  prophesy  regarding  the  future  possi- 
bilities in  the  electrical  world,  but  there  seems  little  doubt 
that  in  time  we  shall  have  a  complete  electrification  of 
our  railways.  Our  present  method  of  making  the  source 
of  power  drive  not  only  itself  along,  but  also  a  heavy 
supply  of  coals  and  water  for  its  own  consumption,  does 
seem  a  very  clumsy  proceeding  when  compared  with  a 
fixed  generating  plant  dispensing  power  in  wholesale 
fashion  to  all  the  trains  upon  a  particular  route.  It  is 
very  remarkable  that  the  trains  have  merely  to  be  in 
contact  with  a  stationary  wire,  which  conducts  current 
from  the  dynamos  to  the  electric  motors  on  board  the 
train.  We  must  look  upon  these  motors  as  merely  con- 

336 


FUTURE  POSSIBILITIES 

verters,  transforming  electrical  energy  into  mechanical 
motion.  There  will,  no  doubt,  be  a  great  increase  in 
speed  on  electrified  railways,  and  it  is  quite  possible  that 
the  ordinary  speeds  of  the  next  generation  would  at 
present  appear  quite  ridiculous  to  us  if  they  could  be 
correctly  predicted.  Our  grandfathers  said  that  people 
would  as  soon  be  shot  off  like  a  Congreve  rocket  as  trust 
themselves  to  the  mercy  of  a  steam  locomotive,  the  speed 
then  being  about  eighteen  miles  per  hour.  Nowadays  we 
ride  at  a  speed  of  fifty  miles  an  hour,  with  an  occasional 
short  run  of  ninety  miles  per  hour. 

It  seems  to  me  very  probable  that  before  another 
generation  has  come  and  gone  people  will  have  no  cause 
to  grumble  at  smoke  and  dirt  in  the  atmosphere  of  cities, 
as  the  whole  energy  required  for  motive  power,  heating, 
and  lighting  may  be  delivered  from  one  great  generating 
station  outside  of  the  city.  When  the  cost  of  electricity 
has  been  greatly  reduced  its  use  will  doubtless  become 
quite  universal,  and  in  future  days  the  housewives  will 
not  have  to  trouble  about  the  making  of  fires  for  heating 
and  cooking.  It  may  be  that  both  the  heating  and 
lighting  will  be  regulated  by  automatic  devices,  which 
even  now  would  be  possible  though  extravagant. 

When  using  the  telephone  of  the  future,  we  need  not  be 
surprised  if,  when  calling  up  a  friend  without  the  aid  of 
exchange  operators,  we  hear  our  friend's  voice  reply  that 
he  has  gone  out  and  does  not  expect  to  be  back  till  late 
in  the  evening,  but  begs  us,  if  it  is  any  message  that  can 
be  left  for  him,  just  to  speak  it  into  this  automatic 
machine  which  is  at  present  speaking,  and  it  will  deliver 
the  message  to  its  master  on  his  return  home. 
Y  337 


FUTURE  POSSIBILITIES 

Doubtless  there  will  be  advances  during  the  next 
century  that  the  mind  of  man  has  not  yet  conceived,  for 
the  patient  research  of  so  many  able  workers  is  bound  to 
be  productive  in  leading  to  further  practical  applications. 
When  Franklin  was  asked  what  use  there  was  in  some  of 
his  experiments,  he  would  reply  in  Scotch  fashion  by  ask- 
ing another  question,  "  What  is  the  use  of  a  baby  ?"  and 
when  the  illustrious  Faraday  was  similarly  questioned  he 
would  say  "  endeavour  to  make  it  useful." 

It  was  only  yesterday  we  knew  nothing  of  X-rays,  wire- 
less telegraphy,  etc.,  and  doubtless  there  are  other  and 
greater  surprises  awaiting  even  the  present  generation  of 
men,  while  those  things  which  we  now  class  under 
"  modern  electricity "  may  ere  long  be  catalogued  as 
"  early  ideas  and  undertakings  in  ether." 


338 


INDEX 


Accumulators,  33,  36,  259 
Agriculture,  138 
Alphabets,  telegraphic,  55, 

57,82 
Alternating  currents,   198, 

200,  205 

Aluminium,  257,  259 
Amber,  22,  334 
Ammeter,  306 
Ampere,  303,  312 
Ampere's  telegraph,  55,  92 
Anemometer,  226 
Annunciators,  117 
Arc,  electric,  193,  275 
Arc-lamp,  183 
Armature,  194 
Arrester,  lightning,  149 
Atlantic  cables,  74,  84 
Atmospheric  electricity,  234 
Atoms,  249,  257,  327,  329 


Attraction,  electrical,  22, 48 
Attraction,  magnetic,  22,48 
Aurora  borealis,  111 

B 

Batteries,  26, 30, 32, 36, 259 
Bell,  electric,  115 
Bell-push,  59,  115,  116 
Blasting,  130 

Block  system  on  railways, 
122 

Board  of  Trade  unit,  311 
Bright,  Sir  Charles,  86 
Brushes,  carbon,  197 
Burglar-alarms,  121 


Cables,  Atlantic,  74 
Canadian  power  station,  222 
Canal  haulage,  218 
Cars,  electric,  213,  218 


339 


INDEX 


Cathode  rays,  178, 179 
Cauterising,  240 
Cavendish,  Hon.  Henry,  302 
Chemical  union,  329 
Chronograph,  131,  228 
Circuit-breakers,  172 
Clergymen  as  inventors,  14-5 
Clocks,  electric,  132,  227 
Coal-cutters,  270 
Coal-mines,    electricity    in, 

263 

Cobalt,  magnetism  in,  45 
Coherer,  98,  133 
Colour,  329 
Combustion,  185 
Commutator,  205 
Complete  circuit,  58 
Conduction,  167 

Conductivity  of  human 
body,  320 

Conductors,  35 

Conjuring,  287 

Continuous  current,  198 

Copper  coil  a  magnet,  47 

Corpuscles,  249,  323 

Coulomb,  312 

Crookes,  Sir  William,  177, 
244 

Cures  by  electricity,  237 


D 

Dalton's  doctrine,  248 
Davy,  Sir  Humphry,   182, 

184,  187,  193,  256,  260, 

275,  334 
Decomposition  of  water,  254, 

259,  260,  329 
Direction  of  current,  316 
Drills,  electric,  210 
Duplex  telegraphy,  69 
Dynamo,  194,  207 

E 

Earth  a  magnet,  40 
Earth  circuit,  59,  61 
Electric  current,  326 
Electric  light,  182 
Electrocution,  134,  319 
Electrodes,  258 
Electrolysis,  258 
Electromagnets,  43, 1 27, 1 94 
Electrons,  323 
Electroplating,  260 
Electrotyping,  261 
Emanation  of  radium,  248 
Energy  transformed,  32 
Ether,   97,  99,   101,   170, 
251,  315,  327 


349 


INDEX 


Faraday,  Michael,  95,  193, 


Fessenden,  97 
Finsen  lamp,  238 
Fire-alarms,  automatic,  119 
Fish,  electric,  112 
Fluorescent  screen,  246 
Fog  dispelled,  137 
Forest,  De,  97 
Franklin,    Benjamin,    106, 

111 

Frog  experiment,  26 
Furnaces,  electric,  275 


Galileo,  94 

Galvani's  discovery,  26 

Galvanometers,    82,    304, 

306 
Generating  stations,  213, 

222 
Gilbert,   Dr.  William,  23, 

332 

Glow-lamps,  187 
Government  and  telegraphs, 

64,93 
Great  Eastern,  79 


H 

Heat,  329 

Heat  and  electricity,  282 

Heat  from  radium,  252 

Heating  by  electricity,  120, 
278 

Henry's  motor,  208 

Henry's  suggested  telegraph, 

56 
High  -  frequency    currents, 

239 

High-pressure  currents,  214 
High-speed  railways,  217 
High-speed  telegraphy,  66, 

70 
Houdin,  Robert,  295 


Incandescent  lamps,  187, 192 
Indicators,  117 
Induction,  167 
Induction  coils,  168 
Insulators,  35 
Irradiation,  188 

K 

Kelvin,  Lord,  77, 81 , 85, 95, 
234,  302,  335 

Kilowatt,  311 


34i 


INDEX 


Launches,  electric,  219 
Ley  den  jar,  35 
Light,  its  nature,  328 
Lightning,  106,  109 
Lindsay,  James  Bowman,  59 
Lines  of  force,  193 
Live  rail,  216,  319 
Lodestone,  21 
Log,  electric,  133 
Lupus,  treatment  of,  238 

M 

Magnetic  alloys,  46 

Magnetic  field,  48,  193 

Magnetic  poles,  38 

Magnetism's  relation  to  elec- 
tricity, 41 

Magneto -electric  machine, 
48,  194 

Marconi,  96 

Matter,  electric  theory  of, 
324 

Measurement  of  electricity^ 
301 

Metallic  filament  lamps,  192 
Meter,  consumption,  308 
Million,  visual,  249 


Mirror  galvanometer,  82 
Molecules,  43,  257 
Monk's  early  telegraph,  87 
Mono-rail  railway,  217 
Morrison,  Charles,  90 
Morse  telegraph,  56 
Motor,  electric,  203,  207 
Motor-car,  electric,  218 
Mountain  air  imitated,  110 
Muscles  stimulated,  238 

N 

Needle  telegraph,  53 
Negative  electricity,  323 
Niagara  Falls,  221 
Nickel,  magnetism  in,  45 

O 

Observatory,  224 
Oersted's  discovery,  41 
Ohm,  304 
Oxygen,  110, 189 
Ozone,  110 

P 

Peat-coal,  278 
Permanent  magnets,  43 
Perpetual  motion,  50,  252 
Personal  equation,  229 


342 


INDEX 


Phonograph,  142 
Phosphorescence,  246 
Pitchblende,  245 
Poker  a  magnet,  43 
Ponton's  telegraph,  85 
Positive  electricity,  324 
Power  from  sun,  211 
Power  stations,  213,  222 
Power  transmission,  209 
Preece,  Sir  William,  96 
Pressure,  303 
Primary  batteries,  82 
Primary  circuit,  171 
Pyrometers,  284 

Q 

Quackery,  237 

R 

Radiant  heat,  329 
Radio-active  bodies,  245 
Radium,  243,  247,  248 
Railings  magnetised,  46 
Railway  block  system,  122 
Railway,  high-speed,  217 
Rate  of  flow,  303 
Relays  for  telegraphs,  68 
Repeaters,  68 


Resistance,  304 
Resistance  of  human  body, 

319 

Ronald's  telegraph,  91 
Rontgen    rays,    175,    178, 

180,  239,  240 
Royal  Institution,  92,  334 


Search-light,  128,  183 
Secondary  batteries,  33,  36, 

259 

Secondary  circuit,  171 
Seismograph,  230 
Shock,    electric,    35,    236, 

319,  320 

Silver-plating,  261 
Siphon  recorder,  82 
Sound,  its  nature,  139 
Speaking  automaton,  141 
Spectrum,  179 
Steinheil's  discovery,  59 
Storage  of  electricity,  34 
Storms,  magnetic,  111 
Sub-stations,  214 
Sun,  energy,  211 
Supply-meter,  308 


343 


INDEX 


Telegraphic  alphabets,  55, 

57 

Telegraphone,  160 
Telegraphy,  53,  62,  65 
Telegraphy,  duplex,  69 
Telegraphy,  early  attempts, 

87 
Telegraphing  handwriting, 

72 

Telegraphy,  multiplex,  70 
Telegraph  versus  Telephone, 

73 

Telegraphy,  wireless,  94 
Telegraphing  photographs, 

135 
Telephone  exchanges,  146, 

152 

Telephone  in  war,  135 
Telephone,  principle  of,  1 43 
Telephony,  wireless,  162 
Thermo-electricity,  213 
Thermometer,  sensitive,  283 
Thermostat,  120 
Thomson,  Sir  William.  See 

Kelvin 

Thunder-clouds,  107 
Torpedoes,  131 


Tramways,  electric,  212 
Transmission  of  power,  209 
Transmitter,  automatic,  67 
Transmutation    of   metals, 
248 

U 

Underground   telegraph 

cables,  69 

Units,  electrical,  303 
Uranium,  245 


Vacuum  tubes,  173, 176, 178 
Visual  million,  249 
Volt,  30S 

Volta's  discovery,  26 
Voltes  pile,  28,  254 
Voltmeter,  306 

W 

Water  decomposition,  254, 

259,  260 

Water-power,  220 
Watt,  310 
Waves,  ether,  286 
Waves,  continuous,  165 
Welding,  electric,  277 


344 


INDEX 


Wind  records,  224 
Wire,  aerial,  103,  166 
Wireless  telegraphy,  94 
Wireless,  principle  of,  97 
Wireless  telegraphy  in  war, 
105 

Wireless  telephony, 


X-rays,  175,  178,  180,  239, 
240 


Zinc  sulphide,  244 


PLTMOCTH;  w.  BBINDOM  AND  sow,  LTD.,  PRINTEIW 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


23NOV59DP 


^~T- 


REC'D  LD 


SEP  2  6  1962 


LD  21A-50w-4,'59 
(A1724slO)476B 


General  Library 

University  of  California 

Berkeley 


YC   I  1 092 


347 


